, photo = Sahara real color.jpg , photo_caption = The Sahara taken by Apollo 17 astronauts, 1972 , map = , map_image = , location = , country = , country1 = , country2 = , country3 = , country4 = , country5 = , country6 = , country7 = , country8 = , country9 = , country10 = ( disputed) , region = , state = , district = , city = , relief = , label = , label_position = , coordinates = , coordinates_ref = , elevation = , elevation_m = , elevation_ft = , elevation_ref = , length = , length_mi = , length_km = 4,800 , length_orientation = , length_note = , width = , width_mi = , width_km = 1,800 , width_orientation = , width_note = , area = , area_mi2 = , area_km2 = 9,200,000 , depth = , depth_ft = , depth_m = , type = , age = , border = , topo = , traversed = , river = , footnotes = , map_size= The Sahara (, ) is a desert on the African continent. With an area of , it is the largest hot desert in the world and the third-largest desert overall, smaller only than the deserts of

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest co ...

and the northern

Arctic The Arctic ( or ) is a polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada ( Yukon, Northwest Territories, Nunavut), Danish Realm ( Greenland), Finland, Iceland ...

. The name "Sahara" is derived from the Arabic word for "desert" in the feminine irregular form, the singular ( ), plural ( ), (), (), (). The desert comprises much of

North Africa North Africa, or Northern Africa is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region, and it is sometimes defined as stretching from the Atlantic shores of Mauritania in t ...

, excluding the fertile region on the

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ...

coast, the

Atlas Mountains The Atlas Mountains are a mountain range in the Maghreb in North Africa. It separates the Sahara Desert from the Mediterranean Sea and the Atlantic Ocean; the name "Atlantic" is derived from the mountain range. It stretches around through Moroc ...

of the Maghreb, and the Nile Valley in

Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Med ...

and the Sudan. It stretches from the

Red Sea The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''Phiom ǹšari''; ...

in the east and the Mediterranean in the north to the

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth#Surface, Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Afr ...

in the west, where the landscape gradually changes from desert to coastal plains. To the south it is bounded by the

Sahel The Sahel (; ar, ساحل ' , "coast, shore") is a region in North Africa. It is defined as the ecoclimatic and biogeographic realm of transition between the Sahara to the north and the Sudanian savanna to the south. Having a hot semi-arid c ...

, a belt of semi-arid tropical savanna around the Niger River valley and the Sudan region of sub-Saharan Africa. The Sahara can be divided into several regions, including the western Sahara, the central

Ahaggar Mountains The Hoggar Mountains ( ar, جبال هقار, Berber: ''idurar n Ahaggar'') are a highland region in the central Sahara in southern Algeria, along the Tropic of Cancer. The mountains cover an area of approximately 550,000 km. Geography This ...

, the Tibesti Mountains, the Aïr Mountains, the Ténéré desert, and the Libyan Desert. For several hundred thousand years, the Sahara has alternated between desert and savanna grassland in a 20,000-year cycle caused by the precession of Earth's axis as it rotates around the Sun, which changes the location of the North African monsoon.

Geography

The Sahara covers large parts of

Algeria ) , image_map = Algeria (centered orthographic projection).svg , map_caption = , image_map2 = , capital = Algiers , coordinates = , largest_city = capital , religi ...

Chad Chad (; ar, تشاد , ; french: Tchad, ), officially the Republic of Chad, '; ) is a landlocked country at the crossroads of North and Central Africa. It is bordered by Libya to the north, Sudan to the east, the Central African Repub ...

Libya Libya (; ar, ليبيا, Lībiyā), officially the State of Libya ( ar, دولة ليبيا, Dawlat Lībiyā), is a country in the Maghreb region in North Africa. It is bordered by the Mediterranean Sea to the north, Egypt to the east, Su ...

Mali Mali (; ), officially the Republic of Mali,, , ff, 𞤈𞤫𞤲𞥆𞤣𞤢𞥄𞤲𞤣𞤭 𞤃𞤢𞥄𞤤𞤭, Renndaandi Maali, italics=no, ar, جمهورية مالي, Jumhūriyyāt Mālī is a landlocked country in West Africa. Ma ...

, Mauritania,

Morocco Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria ...

Niger ) , official_languages = , languages_type = National languagesWestern Sahara, Sudan and

Tunisia ) , image_map = Tunisia location (orthographic projection).svg , map_caption = Location of Tunisia in northern Africa , image_map2 = , capital = Tunis , largest_city = capital , ...

. It covers , amounting to 31% of Africa. If all areas with a mean annual precipitation of less than 250 mm were included, the Sahara would be . It is one of three distinct physiographic provinces of the African massive physiographic division. Sahara is so large and bright that, in theory, it could be detected from other stars as a surface feature of Earth, with near-current technology. The Sahara is mainly rocky hamada (stone plateaus); ergs (sand seas – large areas covered with sand

dune A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, fl ...

s) form only a minor part, but many of the

sand dune A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, f ...

s are over high. Wind or rare rainfall shape the desert features: sand dunes, dune fields, sand seas, stone plateaus, gravel plains (''reg''), dry valleys (''wadi''), dry lakes (''oued''), and salt flats (''shatt'' or ''chott''). Unusual landforms include the Richat Structure in Mauritania. Several deeply dissected mountains, many volcanic, rise from the desert, including the Aïr Mountains,

, Saharan Atlas, Tibesti Mountains,

Adrar des Iforas The Adrar des Ifoghas (also Adrar des Iforas; Tamasheq: ⴰⴷⵔⴰⵔ ⵏ ⵉⴼⵓⵖⴰⵙ in Tifinagh; Adrar n Ifoghas; ar, أدرار إيفوغاس Ifoghas' Mountains) is a massif located in the Kidal Region of Mali, reaching into Algeri ...

, and the Red Sea Hills. The highest peak in the Sahara is Emi Koussi, a shield volcano in the Tibesti range of northern Chad. The central Sahara is hyperarid, with sparse vegetation. The northern and southern reaches of the desert, along with the highlands, have areas of sparse grassland and

desert shrub Deserts and xeric shrublands are a biome defined by the World Wide Fund for Nature. Deserts and xeric (ancient Greek xērós, “dry") shrublands form the largest terrestrial biome, covering 19% of Earth's land surface area. Ecoregions in thi ...

, with trees and taller shrubs in wadis, where moisture collects. In the central, hyperarid region, there are many subdivisions of the great desert: Tanezrouft, the Ténéré, the Libyan Desert, the

Eastern Desert The Eastern Desert (Archaically known as Arabia or the Arabian Desert) is the part of the Sahara desert that is located east of the Nile river. It spans of North-Eastern Africa and is bordered by the Nile river to the west and the Red Sea and ...

, the Nubian Desert and others. These extremely arid areas often receive no rain for years. To the north, the Sahara skirts the

in Egypt and portions of Libya, but in Cyrenaica and the Maghreb, the Sahara borders the Mediterranean forest, woodland, and scrub eco-regions of northern Africa, all of which have a Mediterranean climate characterized by hot summers and cool and rainy winters. According to the botanical criteria of Frank White and geographer Robert Capot-Rey, the northern limit of the Sahara corresponds to the northern limit of date palm cultivation and the southern limit of the range of esparto, a grass typical of the Mediterranean climate portion of the Maghreb and

Iberia The Iberian Peninsula (), ** * Aragonese and Occitan: ''Peninsula Iberica'' ** ** * french: Péninsule Ibérique * mwl, Península Eibérica * eu, Iberiar penintsula also known as Iberia, is a peninsula A peninsula (; ) is a la ...

. The northern limit also corresponds to the isohyet of annual precipitation. To the south, the Sahara is bounded by the Sahel, a belt of dry tropical savanna with a summer rainy season that extends across Africa from east to west. The southern limit of the Sahara is indicated botanically by the southern limit of '' Cornulaca monacantha'' (a drought-tolerant member of the Chenopodiaceae), or northern limit of ''

Cenchrus biflorus ''Cenchrus biflorus'' is a species of annual grass in the family Poaceae. Common names include Indian sandbur, ''Bhurat'' or ''Bhurut'' in India, ''Haskaneet'' in Sudan, ''Aneeti'' in the Arabic dialect of Mauritania, ''K 'arangiya'' in the ...

'', a grass typical of the Sahel. According to climatic criteria, the southern limit of the Sahara corresponds to the isohyet of annual precipitation (this is a long-term average, since precipitation varies annually). Important cities located in the Sahara include Nouakchott, the capital of Mauritania; Tamanrasset, Ouargla, Béchar, Hassi Messaoud, Ghardaïa, and El Oued in Algeria;

Timbuktu Timbuktu ( ; french: Tombouctou; Koyra Chiini: ); tmh, label= Tuareg, script=Tfng, ⵜⵏⴱⴾⵜ, Tin Buqt a city in Mali, situated north of the Niger River. The town is the capital of the Tombouctou Region, one of the eight administrat ...

in Mali;

Agadez Agadez ( Air Tamajeq: ⴰⴶⴰⴷⴰⵣ, ''Agadaz''), formerly spelled Agadès, is the fifth largest city in Niger, with a population of 110,497 based on the 2012 census. The capital of Agadez Region, it lies in the Sahara desert, and is a ...

in Niger; Ghat in Libya; and Faya-Largeau in Chad.

Climate

The Sahara is the world's largest hot desert. It is located in the

horse latitudes The horse latitudes are the latitudes about 30 degrees north and south of the Equator. They are characterized by sunny skies, calm winds, and very little precipitation. They are also known as subtropical ridges, or highs. It is a high-pressu ...

under the

subtropical ridge The horse latitudes are the latitudes about 30 degrees north and south of the Equator. They are characterized by sunny skies, calm winds, and very little precipitation. They are also known as subtropical ridges, or highs. It is a high-pressu ...

, a significant belt of semi-permanent subtropical warm-core high pressure where the air from the upper troposphere usually descends, warming and drying the lower troposphere and preventing cloud formation. The permanent absence of clouds allows unhindered light and thermal radiation. The stability of the atmosphere above the desert prevents any convective overturning, thus making rainfall virtually non-existent. As a consequence, the weather tends to be sunny, dry and stable with a minimal chance of rainfall. Subsiding, diverging, dry air masses associated with subtropical high-pressure systems are extremely unfavorable for the development of convectional showers. The subtropical ridge is the predominant factor that explains the hot desert climate (

Köppen climate classification The Köppen climate classification is one of the most widely used climate classification systems. It was first published by German-Russian climatologist Wladimir Köppen (1846–1940) in 1884, with several later modifications by Köppen, nota ...

''BWh'') of this vast region. The descending airflow is the strongest and the most effective over the eastern part of the Great Desert, in the Libyan Desert: this is the sunniest, driest and the most nearly "rainless" place on the planet, rivaling the

Atacama Desert The Atacama Desert ( es, Desierto de Atacama) is a desert plateau in South America covering a 1,600 km (990 mi) strip of land on the Pacific coast, west of the Andes Mountains. The Atacama Desert is the driest nonpolar desert in the ...

, lying in

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the eas ...

and

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

. The rainfall inhibition and the dissipation of cloud cover are most accentuated over the eastern section of the Sahara rather than the western. The prevailing air mass lying above the Sahara is the continental tropical (cT) air mass, which is hot and dry. Hot, dry air masses primarily form over the North-African desert from the heating of the vast continental land area, and it affects the whole desert during most of the year. Because of this extreme heating process, a thermal low is usually noticed near the surface, and is the strongest and the most developed during the summertime. The

Sahara High , photo = Sahara real color.jpg , photo_caption = The Sahara taken by Apollo 17 astronauts, 1972 , map = , map_image = , location = , country = , country1 = , ...

represents the eastern continental extension of the Azores High, centered over the North Atlantic Ocean. The subsidence of the Sahara High nearly reaches the ground during the coolest part of the year, while it is confined to the upper troposphere during the hottest periods. The effects of local surface low pressure are extremely limited because upper-level subsidence still continues to block any form of air ascent. Also, to be protected against rain-bearing weather systems by the atmospheric circulation itself, the desert is made even drier by its geographical configuration and location. Indeed, the extreme aridity of the Sahara is not only explained by the subtropical high pressure: the

of Algeria, Morocco and Tunisia also help to enhance the aridity of the northern part of the desert. These major mountain ranges act as a barrier, causing a strong rain shadow effect on the leeward side by dropping much of the humidity brought by atmospheric disturbances along the polar front which affects the surrounding Mediterranean climates. The primary source of rain in the Sahara is the Intertropical Convergence Zone, a continuous belt of low-pressure systems near the equator which bring the brief, short and irregular rainy season to the

and southern Sahara. Rainfall in this giant desert has to overcome the physical and atmospheric barriers that normally prevent the production of precipitation. The harsh climate of the Sahara is characterized by: extremely low, unreliable, highly erratic rainfall; extremely high sunshine duration values; high temperatures year-round; negligible rates of relative humidity; a significant

diurnal temperature variation In meteorology, diurnal temperature variation is the variation between a high air temperature and a low temperature that occurs during the same day. Temperature lag Temperature lag is an important factor in diurnal temperature variation: peak ...

; and extremely high levels of potential evaporation which are the highest recorded worldwide.

Temperature

The sky is usually clear above the desert, and the

sunshine duration Sunshine duration or sunshine hours is a climatological indicator, measuring duration of sunshine in given period (usually, a day or a year) for a given location on Earth, typically expressed as an averaged value over several years. It is a gene ...

is extremely high everywhere in the Sahara. Most of the desert has more than 3,600 hours of bright sunshine per year (over 82% of daylight hours), and a wide area in the eastern part has over 4,000 hours of bright sunshine per year (over 91% of daylight hours). The highest values are very close to the theoretical maximum value. A value of 4300 hours (98%) of the time would be recorded in

Upper Egypt Upper Egypt ( ar, صعيد مصر ', shortened to , , locally: ; ) is the southern portion of Egypt and is composed of the lands on both sides of the Nile that extend wikt:downriver, upriver from Lower Egypt in the north to Nubia in the south. ...

(

Aswan Aswan (, also ; ar, أسوان, ʾAswān ; cop, Ⲥⲟⲩⲁⲛ ) is a city in Southern Egypt, and is the capital of the Aswan Governorate. Aswan is a busy market and tourist centre located just north of the Aswan Dam on the east bank of ...

Luxor Luxor ( ar, الأقصر, al-ʾuqṣur, lit=the palaces) is a modern city in Upper (southern) Egypt which includes the site of the Ancient Egyptian city of ''Thebes''. Luxor has frequently been characterized as the "world's greatest open-ai ...

) and in the Nubian Desert ( Wadi Halfa). The annual average direct solar irradiation is around 2,800 kWh/(m² year) in the Great Desert. The Sahara has a huge potential for solar energy production. Algeria Sahara Desert Photo From Drone 5

Algeria Sahara Desert Photo From Drone 5

The high position of the Sun, the extremely low relative humidity, and the lack of

vegetation Vegetation is an assemblage of plant species and the ground cover they provide. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic charact ...

and rainfall make the Great Desert the hottest large region in the world, and the hottest place on Earth during summer in some spots. The average high temperature exceeds during the hottest month nearly everywhere in the desert except at very high altitudes. The world's highest officially recorded average daily high temperature was in a remote desert town in the Algerian Desert called

Bou Bernous Bou Bernous is a village in the commune of Oum El Assel, in Tindouf Province, Algeria ) , image_map = Algeria (centered orthographic projection).svg , map_caption = , image_map2 = , capital ...

, at an elevation of above sea level, and only Death Valley, California rivals it. Other hot spots in Algeria such as Adrar, Timimoun, In Salah, Ouallene,

Aoulef Aoulef ( ar, أولف , translit=Awlaf) is a town and commune and capital of Aoulef District, in Adrar Province, south-central Algeria. According to the 2008 census it has a population of 21,723, up from 15,229 in 1998, with an annual growth rate ...

, Reggane with an elevation between above sea level get slightly lower summer average highs, around during the hottest months of the year. Salah, well known in Algeria for its extreme heat, has average high temperatures of , , and in June, July, August and September respectively. There are even hotter spots in the Sahara, but they are located in extremely remote areas, especially in the Azalai, lying in northern Mali. The major part of the desert experiences around three to five months when the average high strictly exceeds ; while in the southern central part of the desert, there are up to six or seven months when the average high temperature strictly exceeds . Some examples of this are Bilma, Niger and Faya-Largeau, Chad. The annual average daily temperature exceeds everywhere and can approach in the hottest regions year-round. However, most of the desert has a value in excess of . Sunset in Sahara

Sand and ground temperatures are even more extreme. During daytime, the sand temperature is extremely high: it can easily reach or more. A sand temperature of 83.5 °C (182.3 °F) has been recorded in Port Sudan. Ground temperatures of have been recorded in the Adrar of Mauritania and a value of 75 °C (167 °F) has been measured in

Borkou Borku (french: Borkou) or Borgu (') is a region of Central Africa, mostly in Northern Chad, forming part of the transitional zone between the arid wastes of the Sahara and the fertile lands of the central Sudan. It is bounded N. by the Tibesti ...

, northern Chad. Due to lack of cloud cover and very low humidity, the desert usually has high

s between days and nights. However, it is a myth that the nights are especially cold after extremely hot days in the Sahara. On average, nighttime temperatures tend to be cooler than in the daytime. The smallest variations are found along the coastal regions due to high humidity and are often even lower than a difference, while the largest variations are found in inland desert areas where the humidity is the lowest, mainly in the southern Sahara. Still, it is true that winter nights can be cold, as it can drop to the freezing point and even below, especially in high-elevation areas. The frequency of subfreezing winter nights in the Sahara is strongly influenced by the North Atlantic Oscillation (NAO), with warmer winter temperatures during negative NAO events and cooler winters with more frosts when the NAO is positive. This is because the weaker clockwise flow around the eastern side of the subtropical anticyclone during negative NAO winters, although too dry to produce more than negligible precipitation, does reduce the flow of dry, cold air from higher latitudes of Eurasia into the Sahara significantly.

Precipitation

The average annual rainfall ranges from very low in the northern and southern fringes of the desert to nearly non-existent over the central and the eastern part. The thin northern fringe of the desert receives more winter cloudiness and rainfall due to the arrival of low pressure systems over the Mediterranean Sea along the polar front, although very attenuated by the rain shadow effects of the mountains and the annual average rainfall ranges from to . For example,

Biskra Biskra ( ar, بسكرة ; ; Latin Vescera) is the capital city of Biskra Province, Algeria. In 2007, its population was recorded as 307,987. Biskra is located in northeastern Algeria, about 248 miles (400 km) from Algiers, 71 miles (115&n ...

, Algeria, and Ouarzazate, Morocco, are found in this zone. The southern fringe of the desert along the border with the Sahel receives summer cloudiness and rainfall due to the arrival of the Intertropical Convergence Zone from the south and the annual average rainfall ranges from to . For example, Timbuktu, Mali and

, Niger are found in this zone. The vast central hyper-arid core of the desert is virtually never affected by northerly or southerly atmospheric disturbances and permanently remains under the influence of the strongest anticyclonic weather regime, and the annual average rainfall can drop to less than . In fact, most of the Sahara receives less than . Of the of desert land in the Sahara, an area of about (about 31% of the total area) receives an annual average rainfall amount of or less, while some (about 17% of the total area) receives an average of or less. The annual average rainfall is virtually zero over a wide area of some in the eastern Sahara comprising deserts of: Libya, Egypt and Sudan ( Tazirbu, Kufra, Dakhla,

Kharga The Kharga Oasis ( Arabic: , ) ; Coptic: ( "Oasis of Hib", "Oasis of Psoi") is the southernmost of Egypt's five western oases. It is located in the Western Desert, about 200 km (125 miles) to the west of the Nile valley. "Kharga" or ...

, Farafra, Siwa, Asyut, Sohag, Luxor, Aswan,

Abu Simbel Abu Simbel is a historic site comprising two massive rock-cut temples in the village of Abu Simbel ( ar, أبو سمبل), Aswan Governorate, Upper Egypt, near the border with Sudan. It is situated on the western bank of Lake Nasser, about ...

, Wadi Halfa) where the long-term mean approximates per year. Rainfall is very unreliable and erratic in the Sahara as it may vary considerably year by year. In full contrast to the negligible annual rainfall amounts, the annual rates of potential evaporation are extraordinarily high, roughly ranging from per year to more than per year in the whole desert. Nowhere else on Earth has air been found as dry and evaporative as in the Sahara region. However, at least two instances of snowfall have been recorded in Sahara, in February 1979 and December 2016, both in the town of Ain Sefra.

Desertification and prehistoric climate

One theory for the formation of the Sahara is that the monsoon in Northern Africa was weakened because of glaciation during the Quaternary period, starting two or three million years ago. Another theory is that the monsoon was weakened when the ancient Tethys Sea dried up during the Tortonian period around 7 million years. The climate of the Sahara has undergone enormous variations between wet and dry over the last few hundred thousand years, believed to be caused by long-term changes in the

North African climate cycle North African climate cycles have a unique history that can be traced back millions of years. The cyclic climate pattern of the Sahara is characterized by significant shifts in the strength of the North African Monsoon. When the North African Monso ...

that alters the path of the North African Monsoon – usually southward. The cycle is caused by a 41,000-year cycle in which the tilt of the earth changes between 22° and 24.5°. At present (2000), we are in a dry period, but it is expected that the Sahara will become green again in 15,000 years. When the North African monsoon is at its strongest annual precipitation and subsequent vegetation in the Sahara region increase, resulting in conditions commonly referred to as the "

green Sahara The African humid period (AHP) (also known by other names) is a climate period in Africa during the late Pleistocene and Holocene geologic epochs, when northern Africa was wetter than today. The covering of much of the Sahara desert by grasses, ...

". For a relatively weak North African monsoon, the opposite is true, with decreased annual precipitation and less vegetation resulting in a phase of the Sahara climate cycle known as the "desert Sahara". The idea that changes in insolation (solar heating) caused by long-term changes in Earth's orbit are a controlling factor for the long-term variations in the strength of monsoon patterns across the globe was first suggested by Rudolf Spitaler in the late nineteenth century, The hypothesis was later formally proposed and tested by the meteorologist John Kutzbach in 1981. Kutzbach's ideas about the impacts of insolation on global monsoonal patterns have become widely accepted today as the underlying driver of long-term monsoonal cycles. Kutzbach never formally named his hypothesis and as such it is referred to here as the " Orbital Monsoon Hypothesis" as suggested by Ruddiman in 2001. Village Telly in Mali

During the last glacial period, the Sahara was much larger than it is today, extending south beyond its current boundaries. The end of the glacial period brought more rain to the Sahara, from about 8000 BCE to 6000 BCE, perhaps because of low pressure areas over the collapsing ice sheets to the north. Once the ice sheets were gone, the northern Sahara dried out. In the southern Sahara, the drying trend was initially counteracted by the

monsoon A monsoon () is traditionally a seasonal reversing wind accompanied by corresponding changes in precipitation but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with annual latitudinal osci ...

, which brought rain further north than it does today. By around 4200 BCE, however, the monsoon retreated south to approximately where it is today,Sahara's Abrupt Desertification Started by Changes in Earth's Orbit
Accelerated by Atmospheric and Vegetation Feedbacks. leading to the gradual desertification of the Sahara. The Sahara is now as dry as it was about 13,000 years ago. Lake Chad is the remnant of a former inland sea, paleolake Mega-Chad, which existed during the African humid period. At its largest extent, sometime before 5000 BCE, Lake Mega-Chad was the largest of four Saharan paleolakes, and is estimated to have covered an area of 350,000 km². The Sahara pump theory describes this cycle. During periods of a wet or "

Green Sahara The African humid period (AHP) (also known by other names) is a climate period in Africa during the late Pleistocene and Holocene geologic epochs, when northern Africa was wetter than today. The covering of much of the Sahara desert by grasses, ...

", the Sahara becomes a savanna grassland and various flora and fauna become more common. Following inter-pluvial arid periods, the Sahara area then reverts to desert conditions and the flora and fauna are forced to retreat northwards to the

, southwards into

West Africa West Africa or Western Africa is the westernmost region of Africa. The United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, Mau ...

, or eastwards into the Nile Valley. This separates

population Population typically refers to the number of people in a single area, whether it be a city or town, region, country, continent, or the world. Governments typically quantify the size of the resident population within their jurisdiction using ...

s of some of the species in areas with different

climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologica ...

s, forcing them to adapt, possibly giving rise to allopatric speciation. Great green wall map

It is also proposed that humans accelerated the drying-out period from 6000 to 2500 BCE by pastoralists overgrazing available grassland.

Evidence for cycles

The growth of speleothems (which requires rainwater) was detected in Hol-Zakh, Ashalim, Even-Sid, Ma'ale-ha-Meyshar, Ktora Cracks, Nagev Tzavoa Cave, and elsewhere, and has allowed tracking of prehistoric rainfall. The Red Sea coastal route was extremely arid before 140 and after 115 kya (thousands of years ago). Slightly wetter conditions appear at 90–87 kya, but it still was just one tenth the rainfall around 125 kya. In the southern

Negev Desert The Negev or Negeb (; he, הַנֶּגֶב, hanNegév; ar, ٱلنَّقَب, an-Naqab) is a desert and semidesert region of southern Israel. The region's largest city and administrative capital is Beersheba (pop. ), in the north. At its southe ...

speleothems did not grow between 185 and 140 kya ( MIS 6), 110–90 (MIS 5.4–5.2), nor after 85 kya nor during most of the interglacial period (MIS 5.1), the glacial period and

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...

. This suggests that the southern Negev was arid-to-hyper-arid in these periods. During the Last Glacial Maximum (LGM) the Sahara desert was more extensive than it is now with the extent of the tropical forests being greatly reduced, and the lower temperatures reduced the strength of the Hadley Cell. This is a climate cell which causes rising tropical air of the

Inter-Tropical Convergence Zone The Intertropical Convergence Zone (ITCZ ), known by sailors as the doldrums or the calms because of its monotonous windless weather, is the area where the northeast and the southeast trade winds converge. It encircles Earth near the thermal e ...

(ITCZ) to bring rain to the tropics, while dry descending air, at about 20 degrees north, flows back to the equator and brings desert conditions to this region. It is associated with high rates of wind-blown mineral dust, and these dust levels are found as expected in marine cores from the north tropical Atlantic. But around 12,500 BCE the amount of dust in the cores in the Bølling/ Allerød phase suddenly plummets and shows a period of much wetter conditions in the Sahara, indicating a Dansgaard-Oeschger (DO) event (a sudden warming followed by a slower cooling of the climate). The moister Saharan conditions had begun about 12,500 BCE, with the extension of the ITCZ northward in the northern hemisphere summer, bringing moist wet conditions and a savanna climate to the Sahara, which (apart from a short dry spell associated with the Younger Dryas) peaked during the

Holocene thermal maximum The Holocene Climate Optimum (HCO) was a warm period that occurred in the interval roughly 9,000 to 5,000 years ago BP, with a thermal maximum around 8000 years BP. It has also been known by many other names, such as Altithermal, Climatic Optim ...

climatic phase at 4000 BCE when mid-latitude temperatures seem to have been between 2 and 3 degrees warmer than in the recent past. Analysis of Nile River deposited sediments in the delta also shows this period had a higher proportion of sediments coming from the Blue Nile, suggesting higher rainfall also in the Ethiopian Highlands. This was caused principally by a stronger

al circulation throughout the sub-tropical regions, affecting India, Arabia and the Sahara.

Lake Victoria Lake Victoria is one of the African Great Lakes. With a surface area of approximately , Lake Victoria is Africa's largest lake by area, the world's largest tropical lake, and the world's second-largest fresh water lake by surface area after ...

only recently became the source of the White Nile and dried out almost completely around 15 kya. The sudden subsequent movement of the ITCZ southwards with a Heinrich event (a sudden cooling followed by a slower warming), linked to changes with the El Niño-Southern Oscillation cycle, led to a rapid drying out of the Saharan and Arabian regions, which quickly became desert. This is linked to a marked decline in the scale of the Nile floods between 2700 and 2100 BCE.

Ecoregions

The Sahara comprises several distinct

ecoregion An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas o ...

s. With their variations in temperature, rainfall, elevation, and soil, these regions harbor distinct communities of plants and animals. * The

Atlantic coastal desert The Atlantic coastal desert is the westernmost ecoregion in the Sahara Desert of North Africa. It occupies a narrow strip along the Atlantic coast, where the more frequent fog and haze generated offshore by the cool Canary Current provide ...

is a narrow strip along the Atlantic coast where fog generated offshore by the cool Canary Current provides sufficient moisture to sustain a variety of lichens, succulents, and shrubs. It covers an area of in the south of Morocco and Mauritania. * The

North Saharan steppe and woodlands The North Saharan steppe and woodlands is a desert ecoregion, in the deserts and xeric shrublands biome, that forms the northern edge of the Sahara. It extends east and west across Northern Africa, south of the Mediterranean dry woodlands and s ...

is along the northern desert, next to the Mediterranean forests, woodlands, and scrub ecoregions of the northern Maghreb and Cyrenaica. Winter rains sustain shrublands and dry woodlands that form a transition between the Mediterranean climate regions to the north and the hyper-arid Sahara proper to the south. It covers in Algeria, Egypt, Libya, Mauritania, Morocco, and Tunisia. * The Sahara Desert ecoregion covers the hyper-arid central portion of the Sahara where rainfall is minimal and sporadic. Vegetation is rare, and this ecoregion consists mostly of sand dunes (''erg, chech, raoui''), stone plateaus (''hamadas''), gravel plains (''reg''), dry valleys (''wadis''), and salt flats. It covers of: Algeria, Chad, Egypt, Libya, Mali, Mauritania, Niger, and Sudan. * The

South Saharan steppe and woodlands The South Saharan steppe and woodlands, also known as the South Sahara desert, is a deserts and xeric shrublands ecoregion of northern Africa. This band is a transitional region between the Sahara's very arid center (the Sahara desert ecoreg ...

ecoregion is a narrow band running east and west between the hyper-arid Sahara and the Sahel savannas to the south. Movements of the equatorial Intertropical Convergence Zone (ITCZ) bring summer rains during July and August which average but vary greatly from year to year. These rains sustain summer pastures of grasses and herbs, with dry woodlands and shrublands along seasonal watercourses. This ecoregion covers in Algeria, Chad, Mali, Mauritania, and Sudan. * In the West Saharan montane xeric woodlands, several volcanic highlands provide a cooler, moister environment that supports Saharo-Mediterranean woodlands and shrublands. The ecoregion covers , mostly in the Tassili n'Ajjer of Algeria, with smaller enclaves in the Aïr of Niger, the Adrar Plateau of Mauritania, and the

of Mali and Algeria. * The Tibesti-Jebel Uweinat montane xeric woodlands ecoregion consists of the Tibesti and

Jebel Uweinat Mount Uwaynat or Gabal El Uweinat ( ar, جبل العوينات ', Arabic for 'Mountain of the springs') is a mountain range in the area of the Egyptian-Libyan-Sudanese tripoint. Because of thousands of prehistoric rock art sites, it is consider ...

highlands. Higher and more regular rainfall and cooler temperatures support woodlands and shrublands of date palm,

acacia ''Acacia'', commonly known as the wattles or acacias, is a large genus of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa and Australasia. The genus n ...

s, myrtle, oleander, tamarix, and several rare and endemic plants. The ecoregion covers in the Tibesti of Chad and Libya, and Jebel Uweinat on the border of Egypt, Libya, and Sudan. * The Saharan halophytics is an area of seasonally flooded saline depressions which is home to halophytic (salt-adapted) plant communities. The Saharan halophytics cover including: the

Qattara The Qattara Depression ( ar, منخفض القطارة, Munḫafaḍ al-Qaṭṭārah) is a depression in northwestern Egypt, specifically in the Matruh Governorate. The depression is part of the Western Desert of Egypt. The Qattara Depressi ...

and Siwa depressions in northern Egypt, the

Tunisian salt lakes The Tunisian salt lakes are a series of lakes in central Tunisia, lying south of the Atlas Mountains at the northern edge of the Sahara. The lakes include, from east to west, the Chott el Fedjedj, Chott el Djerid, and Chott el Gharsa. Geography ...

of central Tunisia, Chott Melghir in Algeria, and smaller areas of Algeria, Mauritania, and the southern part of Morocco. * The Tanezrouft is one of the Sahara's most arid regions, with no vegetation and very little life. A barren, flat gravel plain, it extends south of Reggane in Algeria towards the Adrar des Ifoghas highlands in northern Mali.

Flora and fauna

The flora of the Sahara is highly diversified based on the bio-geographical characteristics of this vast desert. Floristically, the Sahara has three zones based on the amount of rainfall received – the Northern (Mediterranean), Central and Southern Zones. There are two transitional zones – the Mediterranean-Sahara transition and the Sahel transition zone. The Saharan flora comprises around 2800 species of

vascular plant Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They ...

s. Approximately a quarter of these are

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found els ...

. About half of these species are common to the flora of the Arabian deserts. GueltaCamels

The central Sahara is estimated to include five hundred species of plants, which is extremely low considering the huge extent of the area. Plants such as acacia trees, palms, succulents, spiny shrubs, and grasses have adapted to the arid conditions, by growing lower to avoid water loss by strong winds, by storing water in their thick stems to use it in dry periods, by having long roots that travel horizontally to reach the maximum area of water and to find any surface moisture, and by having small thick leaves or needles to prevent water loss by evapotranspiration. Plant leaves may dry out totally and then recover. Several species of fox live in the Sahara including: the fennec fox, pale fox and Rüppell's fox. The addax, a large white

antelope The term antelope is used to refer to many species of even-toed ruminant that are indigenous to various regions in Africa and Eurasia. Antelope comprise a wastebasket taxon defined as any of numerous Old World grazing and browsing hoofed mamm ...

, can go nearly a year in the desert without drinking. The dorcas gazelle is a north African gazelle that can also go for a long time without water. Other notable gazelles include the rhim gazelle and dama gazelle. The Saharan

cheetah The cheetah (''Acinonyx jubatus'') is a large cat native to Africa and central Iran. It is the fastest land animal, estimated to be capable of running at with the fastest reliably recorded speeds being , and as such has evolved specialized ...

( northwest African cheetah) lives in Algeria,

Togo Togo (), officially the Togolese Republic (french: République togolaise), is a country in West Africa. It is bordered by Ghana to the west, Benin to the east and Burkina Faso to the north. It extends south to the Gulf of Guinea, where its ...

, Niger, Mali,

Benin Benin ( , ; french: Bénin , ff, Benen), officially the Republic of Benin (french: République du Bénin), and formerly Dahomey, is a country in West Africa. It is bordered by Togo to the west, Nigeria to the east, Burkina Faso to the nort ...

, and

Burkina Faso Burkina Faso (, ; , ff, 𞤄𞤵𞤪𞤳𞤭𞤲𞤢 𞤊𞤢𞤧𞤮, italic=no) is a landlocked country in West Africa with an area of , bordered by Mali to the northwest, Niger to the northeast, Benin to the southeast, Togo and Ghana to the ...

. There remain fewer than 250 mature cheetahs, which are very cautious, fleeing any human presence. The cheetah avoids the sun from April to October, seeking the shelter of shrubs such as

balanites ''Balanites'' is an Afrotropical, Palearctic and Indomalayan genus of flowering plants in the caltrop family, Zygophyllaceae. The name ''Balanites'' derives from the Greek word for an acorn and refers to the fruit, it was coined by Alire Del ...

and acacias. They are unusually pale. The other cheetah subspecies ( northeast African cheetah) lives in Chad, Sudan and the eastern region of Niger. However, it is currently extinct in the wild in Egypt and Libya. There are approximately 2000 mature individuals left in the wild. Libya 5391 Ubari Lakes Luca Galuzzi 2007

Libya 5391 Ubari Lakes Luca Galuzzi 2007

Other animals include the

monitor lizard Monitor lizards are lizards in the genus ''Varanus,'' the only extant genus in the family Varanidae. They are native to Africa, Asia, and Oceania, and one species is also found in the Americas as an invasive species. About 80 species are reco ...

s, hyrax, sand vipers, and small populations of African wild dog, in perhaps only 14 countries and red-necked ostrich. Other animals exist in the Sahara (birds in particular) such as African silverbill and black-faced firefinch, among others. There are also small desert crocodiles in Mauritania and the Ennedi Plateau of Chad. The deathstalker scorpion can be long. Its venom contains large amounts of agitoxin and scyllatoxin and is very dangerous; however, a sting from this scorpion rarely kills a healthy adult. The Saharan silver ant is unique in that due to the extreme high temperatures of their habitat, and the threat of predators, the ants are active outside their nest for only about ten minutes per day. Dromedary camels and

goat The goat or domestic goat (''Capra hircus'') is a domesticated species of goat-antelope typically kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a member of ...

s are the domesticated animals most commonly found in the Sahara. Because of its qualities of endurance and speed, the dromedary is the favourite animal used by

nomad A nomad is a member of a community without fixed habitation who regularly moves to and from the same areas. Such groups include hunter-gatherers, pastoral nomads (owning livestock), tinkers and trader nomads. In the twentieth century, the po ...

s. Human activities are more likely to affect the habitat in areas of permanent water (oases) or where water comes close to the surface. Here, the local pressure on natural resources can be intense. The remaining populations of large mammals have been greatly reduced by hunting for food and recreation. In recent years development projects have started in the deserts of Algeria and Tunisia using irrigated water pumped from underground aquifers. These schemes often lead to soil degradation and salinization. Researchers from Hacettepe University have reported that Saharan soil may have bio-available iron and also some essential macro and micro nutrient elements suitable for use as fertilizer for growing wheat.

History

People lived on the edge of the desert thousands of years ago,Discover Magazine
2006-Oct. since the end of the last glacial period. In the Central Sahara, engraved and painted rock art were created perhaps as early as 10,000 years ago, spanning the

Bubaline Period Bubalus, Bubaline, or Large Wild Fauna rock art is the earliest form of Central Saharan rock art, created in an petroglyph, engraved style, which have been dated between 12,000 BCE and 8000 BCE. The Bubaline Period is followed by the Kel Essuf P ...

, Kel Essuf Period, Round Head Period, Pastoral Period, Caballine Period, and Cameline Period. The Sahara was then a much wetter place than it is today. Over 30,000 petroglyphs of river animals such as crocodilesNational Geographic News
17 June 2006. survive, with half found in the Tassili n'Ajjer in southeast Algeria.

Fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s of

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

s, including '' Afrovenator'', '' Jobaria'' and ''

Ouranosaurus ''Ouranosaurus'' is a genus of herbivorous basal hadrosauriform dinosaur that lived during the Aptian stage of the Early Cretaceous of modern-day Niger and Cameroon. ''Ouranosaurus'' measured about long. Two rather complete fossils were found i ...

'', have also been found here. The modern Sahara, though, is not lush in vegetation, except in the

Nile The Nile, , Bohairic , lg, Kiira , Nobiin language, Nobiin: Áman Dawū is a major north-flowing river in northeastern Africa. It flows into the Mediterranean Sea. The Nile is the longest river in Africa and has historically been considered ...

Valley, at a few

oases In ecology, an oasis (; ) is a fertile area of a desert or semi-desert environmentolive tree are found to grow. It was long believed that the region had been this way since about 1600 BCE, after shifts in Earth's axis increased temperatures and decreased precipitation, which led to the abrupt desertification of North Africa about 5,400 years ago.

Kiffians

The Kiffian culture is a prehistoric industry, or domain, that existed between 10,000 and 8,000 years ago in the Sahara, during the Neolithic Subpluvial. Human remains from this culture were found in 2000 at a site known as Gobero, located in

Niger ) , official_languages = , languages_type = National languagesTénéré Desert. The site is known as the largest and earliest grave of Stone Age people in the Sahara desert. The Kiffians were skilled hunters. Bones of many large savannah animals that were discovered in the same area suggest that they lived on the shores of a lake that was present during the Holocene Wet Phase, a period when the Sahara was verdant and wet. The Kiffian people were tall, standing over six feet in height. Craniometric analysis indicates that this early

population was closely related to the Late Pleistocene Iberomaurusians and early Holocene Capsians of the Maghreb, as well as mid-Holocene

Mechta ''Luna 1'', also known as ''Mechta'' (russian: Мечта , '' lit.'': ''Dream''), ''E-1 No.4'' and ''First Lunar Rover'', was the first spacecraft to reach the vicinity of Earth's Moon, and the first spacecraft to be placed in heliocentric or ...

groups. Traces of the Kiffian culture do not exist after 8,000 years ago, as the Sahara went through a dry period for the next thousand years. After this time, the Tenerian culture colonized the area.

Tenerians

Gobero was discovered in 2000 during an archaeological expedition led by Paul Sereno, which sought

remains. Two distinct prehistoric cultures were discovered at the site: the early

Kiffian culture, and the middle Holocene Tenerian culture. The post-Kiffian desiccation lasted until around 4600 BCE, when the earliest artefacts associated with the Tenerians have been dated to. Some 200 skeletons have been discovered at Gobero. The Tenerians were considerably shorter in height and less robust than the earlier Kiffians. Craniometric analysis also indicates that they were osteologically distinct. The Kiffian skulls are akin to those of the Late Pleistocene Iberomaurusians, early Holocene Capsians, and mid-Holocene

groups, whereas the Tenerian crania are more like those of Mediterranean groups. Graves show that the Tenerians observed spiritual traditions, as they were buried with artifacts such as jewelry made of hippo tusks and clay pots. The most interesting find is a triple burial, dated to 5300 years ago, of an adult female and two children, estimated through their teeth as being five and eight years old, hugging each other. Pollen residue indicates they were buried on a bed of flowers. The three are assumed to have died within 24 hours of each other, but as their skeletons hold no apparent trauma (they did not die violently) and they have been buried so elaborately – unlikely if they had died of a plague – the cause of their deaths is a mystery. Vue de Taghit

Tashwinat Mummy

Uan Muhuggiag appears to have been inhabited from at least the 6th millennium BCE to about 2700 BCE, although not necessarily continuously. The most noteworthy find at Uan Muhuggiag is the well-preserved mummy of a young boy of approximately years old. The child was in a fetal position, then embalmed, then placed in a sack made of antelope skin, which was insulated by a layer of leaves. The boy's organs were removed, as evidenced by incisions in his stomach and thorax, and an organic preservative was inserted to stop his body from decomposing. An ostrich eggshell necklace was also found around his neck. Radiocarbon dating determined the age of the mummy to be approximately 5600 years old, which makes it about 1000 years older than the earliest previously recorded mummy in ancient

. In 1958–59, an archaeological expedition led by Antonio Ascenzi conducted anthropological, radiological, histological and chemical analyses on the Uan Muhuggiag mummy. The team claimed that the mummy was a 30-month-old child of uncertain sex who possessed Negroid features (Note: "negroid" is derived from a disproven theory of biological race, and modern genetics has since rendered such terminology obsolete). A long incision on the specimen's abdominal wall also indicated that the body had been initially mummified by evisceration and later underwent natural desiccation. One other individual, an adult, was found at Uan Muhuggiag, buried in a crouched position. However, the body showed no evidence of evisceration or any other method of preservation. The body was estimated to date from about 7500 BP.

Nubians

During the

Neolithic The Neolithic period, or New Stone Age, is an Old World archaeological period and the final division of the Stone Age. It saw the Neolithic Revolution, a wide-ranging set of developments that appear to have arisen independently in several part ...

Era, before the onset of desertification around 9500 BCE, the central Sudan had been a rich environment supporting a large population ranging across what is now barren desert, like the Wadi el-Qa'ab. By the 5th millennium BCE, the people who inhabited what is now called

Nubia Nubia () (Nobiin language, Nobiin: Nobīn, ) is a region along the Nile river encompassing the area between the Cataracts of the Nile, first cataract of the Nile (just south of Aswan in southern Egypt) and the confluence of the Blue Nile, Blue ...

were full participants in the "agricultural revolution", living a settled lifestyle with domesticated plants and animals. Saharan rock art of cattle and herdsmen suggests the presence of a

cattle cult Due to the multiple benefits from cattle, there are varying beliefs about cattle in societies and religions. In some regions, especially most states of India, the slaughter of cattle is prohibited and their meat may be taboo. Cattle are consider ...

like those found in Sudan and other pastoral societies in Africa today. Megaliths found at Nabta Playa are overt examples of probably the world's first known archaeoastronomy devices, predating Stonehenge by some 2,000 years. This complexity, as observed at Nabta Playa, and as expressed by different levels of authority within the society there, likely formed the basis for the structure of both the Neolithic society at Nabta and the Old Kingdom of Egypt. Archaeological evidence has attested that population settlements occurred in Nubia as early as the Late Pleistocene era and from the 5th millennium BC onwards, whereas there is "no or scanty evidence" of human presence in the Egyptian Nile Valley during these periods, which may be due to problems in site preservation.

Egyptians

By 6000 BCE predynastic Egyptians in the southwestern corner of Egypt were herding cattle and constructing large buildings. Subsistence in organized and permanent settlements in predynastic Egypt by the middle of the 6th millennium BCE centered predominantly on cereal and animal agriculture: cattle, goats, pigs and sheep. Metal objects replaced prior ones of stone. Tanning of animal skins, pottery and weaving were commonplace in this era also. There are indications of seasonal or only temporary occupation of the Al Fayyum in the 6th millennium BCE, with food activities centering on fishing, hunting and food-gathering. Stone arrowheads, knives and scrapers from the era are commonly found.Fayum, Qarunian
(Fayum B, about 6000–5000 BCE?)
Digital Egypt
Burial items included pottery, jewelry, farming and hunting equipment, and assorted foods including dried meat and fruit. Burial in desert environments appears to enhance Egyptian preservation rites, and the dead were buried facing due west.Predynastic (5,500–3,100 BCE), Tour Egypt. Several scholars have argued that the African origins of the Egyptian civilisation derived from pastoral communities which emerged in both the Egyptian and Sudanese regions of the Nile Valley in the fifth millennium BCE. By 3400 BCE, the Sahara was as dry as it is today, due to reduced precipitation and higher temperatures resulting from a shift in Earth's orbit. As a result of this aridification, it became a largely impenetrable barrier to humans, with the remaining settlements mainly being concentrated around the numerous oases that dot the landscape. Little trade or commerce is known to have passed through the interior in subsequent periods, the only major exception being the Nile Valley. The Nile, however, was impassable at several cataracts, making trade and contact by boat difficult.

Tichitt culture

In 4000 BCE, the start of sophisticated social structure (e.g., trade of cattle as valued assets) developed among herders amid the Pastoral Period of the Sahara. Saharan pastoral culture (e.g., fields of tumuli, lustrous stone rings, axes) was intricate. By 1800 BCE, Saharan pastoral culture expanded throughout the Saharan and Sahelian regions. The initial stages of sophisticated social structure among Saharan herders served as the segue for the development of sophisticated hierarchies found in African settlements, such as

Dhar Tichitt Dhar Tichitt is a Neolithic archaeological site located in the southwestern region of the Sahara Desert, in Mauritania. It is one of several settlement locations along the sandstone cliffs in the area. Dhar Tichitt, Dhar Walata, Dhar Néma, and ...

. After migrating from the Central Sahara, Mande peoples established their civilization in the Tichitt region of the Western Sahara The Tichitt Tradition of eastern Mauritania dates from 2200 BCE to 200 BCE. Tichitt culture, at Dhar Néma, Dhar Tagant, Dhar Tichitt, and Dhar Walata, included a four-tiered hierarchal social structure,

farming Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled peop ...

cereals A cereal is any grass cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, germ, and bran. Cereal grain crops are grown in greater quantities and provide more foo ...

metallurgy Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys. Metallurgy encompasses both the sci ...

, numerous funerary tombs, and a rock art tradition At Dhar Tichitt and Dhar Walata, pearl millet may have also been independently tamed amid the

. The urban Tichitt Tradition may have been the earliest large-scale, complexly organized society in

, and an early

civilization A civilization (or civilisation) is any complex society characterized by the development of a state, social stratification, urbanization, and symbolic systems of communication beyond natural spoken language (namely, a writing system). C ...

of the Sahara, which may have served as the segue for state formation in West Africa. As areas where the Tichitt cultural tradition were present, Dhar Tichitt and Dhar Walata were occupied more frequently than Dhar Néma. Farming of crops (e.g.,

millet Millets () are a highly varied group of small-seeded grasses, widely grown around the world as cereal crops or grains for fodder and human food. Most species generally referred to as millets belong to the tribe Paniceae, but some millets ...

) may have been a feature of the Tichitt cultural tradition as early as 3rd millennium BCE in Dhar Tichitt. As part of a broader trend of iron metallurgy developed in the West African Sahel amid 1st millennium BCE, iron items (350 BCE – 100 CE) were found at Dhar Tagant, iron metalworking and/or items (800 BCE – 400 BCE) were found at Dia Shoma and Walaldé, and the iron remnants (760 BCE – 400 BCE) found at Bou Khzama and Djiganyai. The iron materials that were found are evidence of iron metalworking at Dhar Tagant. In the late period of the Tichitt Tradition at Dhar Néma, tamed pearl millet was used to temper the tuyeres of a oval-shaped low shaft furnace; this furnace was one out of 16 iron furnaces located on elevated ground. Iron metallurgy may have developed before the second half of 1st millennium BCE, as indicated by pottery dated between 800 BCE and 200 BCE. At Dhar Walata and Dhar Tichitt,

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish ...

was also used. After its decline in Mauritania, the Tichitt Tradition spread to the Middle Niger region (e.g., Méma, Macina, Dia Shoma,

Jenne Jeno Jenne can refer to: *Djenné, a city of Mali * Jenne, Lazio, a city and comune in the Metropolitan City of Rome, Italy People with the given name * Jenne Langhout (1918–2010), Dutch field hockey player * Jenne Lennon (), American singer People ...

) of Mali where it developed into and persisted as Faïta Facies ceramics between 1300 BCE and 400 BCE among rammed earth architecture and iron metallurgy (which had developed after 900 BCE). Thereafter, the Ghana Empire developed in the 1st millennium CE.

Phoenicians

The people of

Phoenicia Phoenicia () was an ancient thalassocratic civilization originating in the Levant region of the eastern Mediterranean, primarily located in modern Lebanon. The territory of the Phoenician city-states extended and shrank throughout their his ...

, who flourished from 1200 to 800 BCE, created a chain of settlements along the coast of North Africa and traded extensively with its inhabitants. This put them in contact with the people of ancient Libya, who were the ancestors of people who speak Berber languages in North Africa and the Sahara today. The Libyco-Berber alphabet of the ancient Libyans of north Africa seems to have been based on Phoenician, and its descendant Tifinagh is still used today by the (Berber) Tuareg of the central Sahara. The Periplus of the Phoenician navigator Hanno, who lived sometime in the 5th century BC, claims that he founded settlements along the Atlantic coast of Africa, possibly including the Western Sahara. The identification of the places discussed is controversial, and archeological confirmation is lacking.

Greeks

By 500 BCE,

Greeks The Greeks or Hellenes (; el, Έλληνες, ''Éllines'' ) are an ethnic group and nation indigenous to the Eastern Mediterranean and the Black Sea regions, namely Greece, Greek Cypriots, Cyprus, Greeks in Albania, Albania, Greeks in Italy, ...

arrived in the desert. Greek traders spread along the eastern coast of the desert, establishing trading colonies along the

. The Carthaginians explored the Atlantic coast of the desert, but the turbulence of the waters and the lack of markets caused a lack of presence further south than modern Morocco. Centralized states thus surrounded the desert on the north and east; it remained outside the control of these states. Raids from the nomadic Berber people of the desert were of constant concern to those living on the edge of the desert.

Urban civilization

An urban civilization, the Garamantes, arose around 500 BCE in the heart of the Sahara, in a valley that is now called the

Wadi al-Ajal Wadi ( ar, وَادِي, wādī), alternatively ''wād'' ( ar, وَاد), North African Arabic Oued, is the Arabic term traditionally referring to a valley. In some instances, it may refer to a wet (ephemeral) riverbed that contains water onl ...

in Fezzan, Libya. The Garamantes achieved this development by digging tunnels far into the mountains flanking the valley to tap fossil water and bring it to their fields. The Garamantes grew populous and strong, conquering their neighbors and capturing many slaves (who were put to work extending the tunnels). The ancient Greeks and the Romans knew of the Garamantes and regarded them as uncivilized nomads. However, they traded with them, and a Roman bath has been found in the Garamantes' capital of Garama. Archaeologists have found eight major towns and many other important settlements in the Garamantes' territory. The Garamantes' civilization eventually collapsed after they had depleted available water in the aquifers and could no longer sustain the effort to extend the tunnels further into the mountains. Between the first century BCE and the fourth century CE, several Roman expeditions into the Sahara were conducted by groups of military and commercial units of Romans.

Berbers

The

Berber people , image = File:Berber_flag.svg , caption = The Berber flag, Berber ethnic flag , population = 36 million , region1 = Morocco , pop1 = 14 million to 18 million , region2 = Algeria , p ...

occupied (and still occupy with Arabs) much of the Sahara. The Garamantes Berbers built a prosperous empire in the heart of the desert. The Tuareg nomads continue to inhabit and move across wide Sahara surfaces to the present day.

Islamic and Arabic expansion

The

Byzantine Empire The Byzantine Empire, also referred to as the Eastern Roman Empire or Byzantium, was the continuation of the Roman Empire primarily in its eastern provinces during Late Antiquity and the Middle Ages, when its capital city was Constantin ...

ruled the northern shores of the Sahara from the 5th to the 7th centuries. After the Muslim conquest of Arabia, specifically the Arabian peninsula, the Muslim conquest of North Africa began in the mid-7th to early 8th centuries and Islamic influence expanded rapidly on the Sahara. By the end of 641 all of Egypt was in Muslim hands. Trade across the desert intensified, and a significant slave trade crossed the desert. It has been estimated that from the 10th to 19th centuries some 6,000 to 7,000 slaves were transported north each year. The Beni Ḥassān and other nomadic Arab tribes dominated the

Sanhaja The Sanhaja ( ber, Aẓnag, pl. Iẓnagen, and also Aẓnaj, pl. Iẓnajen; ar, صنهاجة, ''Ṣanhaja'' or زناگة ''Znaga'') were once one of the largest Berber tribal confederations, along with the Zanata and Masmuda confederations. M ...

Berber tribes of the western Sahara after the Char Bouba war of the 17th century. As a result, Arabian culture and language came to dominate, and the Berber tribes underwent some Arabization.

Ottoman Turkish era

In the 16th century the northern fringe of the Sahara, such as coastal regencies in present-day

Algeria ) , image_map = Algeria (centered orthographic projection).svg , map_caption = , image_map2 = , capital = Algiers , coordinates = , largest_city = capital , religi ...

and Tunisia, as well as some parts of present-day Libya, together with the semi-autonomous kingdom of Egypt, were occupied by the

Ottoman Empire The Ottoman Empire, * ; is an archaic version. The definite article forms and were synonymous * and el, Оθωμανική Αυτοκρατορία, Othōmanikē Avtokratoria, label=none * info page on book at Martin Luther University) ...

. From 1517 Egypt was a valued part of the Ottoman Empire, ownership of which provided the Ottomans with control over the Nile Valley, the east Mediterranean and North Africa. The benefit of the Ottoman Empire was the freedom of movement for citizens and goods. Traders exploited the Ottoman land routes to handle the spices, gold and silk from the East, manufactured goods from Europe, and the slave and gold traffic from Africa. Arabic continued as the local language and Islamic culture was much reinforced. The Sahel and southern Sahara regions were home to several independent states or to roaming Tuareg clans.

European colonialism

European colonialism in the Sahara began in the 19th century.

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan ar ...

conquered the regency of Algiers from the Ottomans in 1830, and French rule spread south from

French Algeria French Algeria (french: Alger to 1839, then afterwards; unofficially , ar, الجزائر المستعمرة), also known as Colonial Algeria, was the period of French colonisation of Algeria. French rule in the region began in 1830 with the ...

and eastwards from

Senegal Senegal,; Wolof: ''Senegaal''; Pulaar: 𞤅𞤫𞤲𞤫𞤺𞤢𞥄𞤤𞤭 (Senegaali); Arabic: السنغال ''As-Sinighal'') officially the Republic of Senegal,; Wolof: ''Réewum Senegaal''; Pulaar : 𞤈𞤫𞤲𞤣𞤢𞥄𞤲𞤣� ...

into the upper

Niger ) , official_languages = , languages_type = National languagesFrench Sudan including

(1893), Mauritania, Morocco (1912), Niger, and Tunisia (1881). By the beginning of the 20th century, the trans-Saharan trade had clearly declined because goods were moved through more modern and efficient means, such as airplanes, rather than across the desert. The French took advantage of long-standing animosity between the Chaamba Arabs and the Tuareg. The newly raised ''Méhariste'' camel corps were originally recruited mainly from the Chaamba nomadic tribe. In 1902, the French penetrated Hoggar Mountains and defeated Ahaggar Tuareg in the battle of Tit. Scramble-for-Africa-1880-1913

The French Colonial Empire was the dominant presence in the Sahara. It established regular air links from

Toulouse Toulouse ( , ; oc, Tolosa ) is the Prefectures in France, prefecture of the Departments of France, French department of Haute-Garonne and of the larger Regions of France, region of Occitania (administrative region), Occitania. The city is on t ...

(HQ of famed Aéropostale), to Oran and over the Hoggar to Timbuktu and West to

Bamako Bamako ( bm, ߓߡߊ߬ߞߐ߬ ''Bàmakɔ̌'', ff, 𞤄𞤢𞤥𞤢𞤳𞤮 ''Bamako'') is the capital and largest city of Mali, with a 2009 population of 1,810,366 and an estimated 2022 population of 2.81 million. It is located on the Niger River ...

and

Dakar Dakar ( ; ; wo, Ndakaaru) (from daqaar ''tamarind''), is the capital and largest city of Senegal. The city of Dakar proper has a population of 1,030,594, whereas the population of the Dakar metropolitan area is estimated at 3.94 million in ...

, as well as trans-Sahara bus services run by La Compagnie Transsaharienne (est. 1927). A remarkable film shot by famous aviator Captain

René Wauthier René ('' born again'' or ''reborn'' in French) is a common first name in French-speaking, Spanish-speaking, and German-speaking countries. It derives from the Latin name Renatus. René is the masculine form of the name (Renée being the feminin ...

documents the first crossing by a large truck convoy from Algiers to Tchad, across the Sahara. Egypt, under Muhammad Ali and his successors, conquered Nubia in 1820–22, founded Khartoum in 1823, and conquered Darfur in 1874. Egypt, including the Sudan, became a British protectorate in 1882. Egypt and Britain lost control of the Sudan from 1882 to 1898 as a result of the Mahdist War. After its capture by British troops in 1898, the Sudan became an Anglo-Egyptian

condominium A condominium (or condo for short) is an ownership structure whereby a building is divided into several units that are each separately owned, surrounded by common areas that are jointly owned. The term can be applied to the building or complex ...

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = '' Plus ultra'' ( Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , ...

captured present-day Western Sahara after 1874, although Rio del Oro remained largely under Sahrawi influence. In 1912,

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...

captured parts of what was to be named

from the Ottomans. To promote the

Roman Catholic Roman or Romans most often refers to: *Rome, the capital city of Italy *Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of ancient Rome *''Epistle to the Romans'', shortened to ''Romans'', a letter ...

religion in the desert, Pope Pius IX appointed a delegate Apostolic of the Sahara and the Sudan in 1868; later in the 19th century his jurisdiction was reorganized into the

Vicariate Apostolic of Sahara The Vicariate Apostolic of Sahara ( la, Vicariatus Apostolicus Saharensis) is a former Roman Catholic missionary jurisdiction in colonial Algeria and Libya. History The Sahara is a vast desert of northern Africa, measuring about 932 miles from nor ...

Breakup of the empires and afterwards

Libya 5101 Fozzigiaren Arch Tadrart Acacus Luca Galuzzi 2007

Egypt became independent of Britain in 1936, although the Anglo-Egyptian treaty of 1936 allowed Britain to keep troops in Egypt and to maintain the British-Egyptian condominium in the Sudan. British military forces were withdrawn in 1954. Most of the Saharan states achieved independence after

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...

: Libya in 1951; Morocco, Sudan, and Tunisia in 1956; Chad, Mali, Mauritania, and Niger in 1960; and Algeria in 1962. Spain withdrew from Western Sahara in 1975, and it was partitioned between Mauritania and Morocco. Mauritania withdrew in 1979; Morocco continues to hold the territory (see Western Sahara conflict).

Tuareg people The Tuareg people (; also spelled Twareg or Touareg; endonym: ''Imuhaɣ/Imušaɣ/Imašeɣăn/Imajeɣăn'') are a large Berber ethnic group that principally inhabit the Sahara in a vast area stretching from far southwestern Libya to southern A ...

in Mali rebelled several times during the 20th century before finally forcing the Malian armed forces to withdraw below the line demarcating

Azawad Azawad, or Azawagh ( Tuareg: Azawaɣ, or Azawad; ar, أزواد) was a short-lived unrecognised state from 2012 to 2013. Azawagh (''Azawaɣ'') is the generic Tuareg Berber name of all Tuareg Berber areas, especially the northern half of M ...

from southern Mali during the 2012 rebellion. Islamist rebels in the Sahara calling themselves al-Qaeda in the Islamic Maghreb have stepped up their violence in recent years. In the post–World War II era, several mines and communities have developed to use the desert's natural resources. These include large deposits of oil and

natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon ...

in Algeria and Libya, and large deposits of phosphates in Morocco and Western Sahara. Libya's Great Man-Made River is the world's largest irrigation project. The project uses a pipeline system that pumps fossil water from the

Nubian Sandstone Aquifer System The Nubian Sandstone Aquifer System (NSAS) is the world's largest known fossil water aquifer system. It is located underground in the Eastern end of the Sahara desert and spans the political boundaries of four countries in north-eastern Africa. N ...

to cities in the populous Libyan northern Mediterranean coast including Tripoli and Benghazi. A number of Trans-African highways have been proposed across the Sahara, including the Cairo–Dakar Highway along the Atlantic coast, the Trans-Sahara Highway from Algiers on the Mediterranean to Kano in Nigeria, the

Tripoli – Cape Town Highway Tripoli or Tripolis may refer to: Cities and other geographic units Greece *Tripoli, Greece, the capital of Arcadia, Greece *Tripolis (region of Arcadia), a district in ancient Arcadia, Greece * Tripolis (Larisaia), an ancient Greek city in t ...

from

Tripoli Tripoli or Tripolis may refer to: Cities and other geographic units Greece *Tripoli, Greece, the capital of Arcadia, Greece *Tripolis (region of Arcadia), a district in ancient Arcadia, Greece * Tripolis (Larisaia), an ancient Greek city in t ...

in Libya to

N'Djamena N'Djamena ( ) is the capital city, capital and largest city of Chad. It is also a Regions of Chad, special statute region, divided into 10 districts or ''arrondissements''. The city serves as the centre of economic activity in Chad. Meat, fish a ...

in Chad, and the Cairo – Cape Town Highway which follows the Nile. Each of these highways is partially complete, with significant gaps and unpaved sections.

People, culture, and languages

The people of the Sahara are of various origins. Among them the Amazigh including the Tuareg, various Arabized Amaziɣ groups such as the Hassaniya-speaking Sahrawis, whose populations include the Znaga, a tribe whose name is a remnant of the pre-historic Zenaga language. Other major groups of people include the: Toubou, Nubians, Zaghawa, Kanuri, Hausa, Songhai, Beja, and Fula/Fulani (french: Peul; ff, Fulɓe). The archaeological evidence from the Holocene period has shown that Nilo-Saharan speaking groups had populated the central and southern Sahara before the influx of Berber and

Arabic Arabic (, ' ; , ' or ) is a Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Watson; Walte ...

speakers, around 1500 years ago, who now largely populate the Sahara in the modern era. Arabic dialects are the most widely spoken languages in the Sahara. Arabic, Berber and its variants now regrouped under the term Amazigh (which includes the Guanche language spoken by the original Berber inhabitants of the Canary Islands) and Beja languages are part of the Afro-Asiatic or

Hamito-Semitic The Afroasiatic languages (or Afro-Asiatic), also known as Hamito-Semitic, or Semito-Hamitic, and sometimes also as Afrasian, Erythraean or Lisramic, are a language family of about 300 languages that are spoken predominantly in the geographic su ...

family. Unlike neighboring

and the central governments of the states that comprise the Sahara, the French language bears little relevance to inter-personal discourse and commerce within the region, its people retaining staunch ethnic and political affiliations with Tuareg and Berber leaders and culture. The legacy of the French colonial era administration is primarily manifested in the territorial reorganization enacted by the Third and Fourth republics, which engendered artificial political divisions within a hitherto isolated and porous region. Diplomacy with local clients was conducted primarily in Arabic, which was the traditional language of bureaucratic affairs. Mediation of disputes and inter-agency communication was served by interpreters contracted by the French government, who, according to Keenan, "documented a space of intercultural mediation," contributing much to preserving the indigenous cultural identities in the region.Jeremy Keenan, ed. (2013). ''The Sahara: Past, Present and Future''. Routledge,

Notes

References

Bibliography

* * Republished with a new preface Columbia University Press, 1990. * * * * * *

External links

About Sahara subsurface aquifers">hydrology">About Sahara subsurface hydrology
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