Ancestral North Indians

The Indo-Aryan migrations were the migrations into the Indian subcontinent of Indo-Aryan peoples, an ethnolinguistic group that spoke Indo-Aryan languages, the predominant languages of today's North India, Pakistan, Nepal, Bangladesh, Sri Lanka and the Maldives. Indo-Aryan population movements into the region from Central Asia are considered to have started after 2000 BCE, as a slow diffusion during the Late Harappan period, which led to a language shift in the northern Indian subcontinent. Several hundred years later, the Iranian languages were brought into the Iranian plateau by the Iranians, who were closely related to the Indo-Aryans.

The Proto-Indo-Iranian culture, which gave rise to the Indo-Aryans and Iranians, developed on the Central Asian steppes north of the Caspian Sea as the Sintashta culture (2050Lindner, Stephan, (2020)
"Chariots in the Eurasian Steppe: a Bayesian approach to the emergence of horse-drawn transport in the early second millennium BC"
in Antiquity, Vol 94, Issue 374, April 2020, p. 367: "...The 12 calibrated radiocarbon dates belonging to the Sintashta horizon range between 2050 and 1760 cal BC (at 95.4% confidence; Epimakhov & Krause 2013: 137). These dates correlate well with the seven AMS-sampled Sintashta graves in the associated KA-5cemetery, which date to 2040–1730 cal BC (95.4% confidence...)".–1800 BCE) in present-day Russia and Kazakhstan, and developed further as the Andronovo culture (2000–1450 BCE).Grigoriev, Stanislav, (2021)
"Andronovo Problem: Studies of Cultural Genesis in the Eurasian Bronze Age"
in Open Archaeology 2021 (7), p.3: "...By Andronovo cultures we may understand only Fyodorovka and Alakul cultures..."Parpola, Asko, (2020)
"Royal 'Chariot' Burials of Sanauli near Delhi and Archaeological Correlates of Prehistoric Indo-Iranian Languages"
in Studia Orientalia Electronica, Vol. 8, No. 1, Oct 23, 2020, p.188: "...the Alakul’ culture (c.2000–1700 BCE) in the west and the Fëdorovo culture(c.1850–1450 BCE) in the east..."

The Indo-Aryans split off sometime between 2000 BCE and 1600 BCE from the Indo-Iranians,Lubotsky, Alexander (2020)
"What language was spoken by the people of the Bactria-Margiana Archaeological Complex?"
in Paul W. Kroll and Jonathan A. Silk (eds.), ''At the Shores of the Sky': Asian Studies for Albert Hoffstädt'', Brill, Leiden/Boston, p. 6: "The breakdown of the Indo-Iranian branch into Indian and Iranian occurred somewhere between 2000 and 1600 bce, when future Indians left their tribesmen and crossed the Hindu Kush on their way to India..." and migrated southwards to the Bactria–Margiana culture (BMAC), from which they borrowed some of their distinctive religious beliefs and practices. From the BMAC, the Indo-Aryans migrated into northern Syria and, possibly in multiple waves, into the Punjab (northern Pakistan and India), while the Iranians could have reached western Iran before 1300 BCE, both bringing with them the Indo-Iranian languages.

Migration by an Indo-European people was first hypothesized in the late 18th century, following the discovery of the Indo-European language family, when similarities between western and Indian languages had been noted. Given these similarities, a single source or origin was proposed, which was diffused by migrations from some original homeland.

This linguistic argument of this theory is supported by archaeological, anthropological, genetic, literary and ecological research. Genetic research reveals that those migrations form part of a complex genetic puzzle on the origin and spread of the various components of the Indian population. Literary research reveals similarities between various, geographically distinct, Indo-Aryan historical cultures. Ecological studies reveal that in the second millennium BCE widespread aridization led to water shortages and ecological changes in both the Eurasian steppes and the Indian subcontinent, causing the collapse of sedentary urban cultures in south central Asia, Afghanistan, Iran, and India, and triggering large-scale migrations, resulting in the merger of migrating peoples with the post-urban cultures.

The Indo-Aryan migrations started sometime in the period from approximately 2000 to 1600 BCE, after the invention of the war chariot, and also brought Indo-Aryan languages into the Levant and possibly Inner Asia. It was part of the diffusion of Indo-European languages from the proto-Indo-European homeland at the Pontic–Caspian steppe, a large area of grasslands in far Eastern Europe, which started in the 5th to 4th millennia BCE, and the Indo-European migrations out of the Eurasian Steppes, which started approximately in 2000 BCE.

These Indo-Aryan speaking people were united by shared cultural norms and language, referred to as ''ārya'', "noble". Diffusion of this culture and language took place by patron-client systems, which allowed for the absorption and acculturation of other groups into this culture, and explains the strong influence on other cultures with which it interacted.

Fundamentals

The Indo-Aryan migration theory is part of a larger theoretical framework. This framework explains the similarities between a wide range of contemporary and ancient languages. It combines linguistic, archaeological and anthropological research. This provides an overview of the development of Indo-European languages, and the spread of these Indo-European languages by migration and acculturation.

Linguistics: relationships between languages

The linguistic part traces the connections between the various Indo-European languages, and reconstructs the proto-Indo-European language. This is possible because the processes that change languages are not random, but follow strict patterns. Sound shifts, the changing of vowels and consonants, are especially important, although grammar (especially morphology) and the lexicon (vocabulary) may also be significant. Historical-comparative linguistics thus makes it possible to see great similarities between related languages which at first sight might seem very different. Various characteristics of the Indo-European languages argue against an Indian origin of these languages, and point to a steppe origin.

Archaeology: migrations from the steppe Urheimat

The archaeological part posits an "Urheimat" on the Pontic steppes, which developed after the introduction of cattle on the steppes around 5,200 BCE. This introduction marked the change from foragist to pastoralist cultures, and the development of a hierarchical social system with chieftains, patron-client systems, and the exchange of goods and gifts. The oldest nucleus may have been the Samara culture (late 6th and early 5th millennium BCE), at a bend in the Volga.

A wider "horizon" developed, called the Kurgan culture by Marija Gimbutas in the 1950s. She included several cultures in this "Kurgan Culture", including the Samara culture and the Yamna culture, although the Yamna culture (36th–23rd centuries BCE), also called "Pit Grave Culture", may more aptly be called the "nucleus" of the proto-Indo-European language. From this area, which already included various subcultures, Indo-European languages spread west, south and east starting around 4,000 BCE. These languages may have been carried by small groups of males, with patron-client systems which allowed for the inclusion of other groups into their cultural system.

Eastward emerged the Sintashta culture (2050–1900 BCE), where common Indo-Iranian was spoken. Out of the Sintashta culture developed the Andronovo culture (2000–1450 BCE), which interacted with the Bactria-Margiana culture (2250–1700 BCE). This interaction further shaped the Indo-Iranians, which split at sometime between 2000 and 1600 BCE into the Indo-Aryans and the Iranians. The Indo-Aryans migrated to the Levant and South Asia. The migration into northern India was not a large-scale immigration, but may have consisted of small groups which were genetically diverse. Their culture and language spread by the same mechanisms of acculturalisation, and the absorption of other groups into their patron-client system.

Anthropology: elite recruitment and language shift

Indo-European languages probably spread through language shifts. Small groups can change a larger cultural area, and elite male dominance by small groups may have led to a language shift in northern India.

David Anthony, in his "revised Steppe hypothesis" notes that the spread of the Indo-European languages probably did not happen through "chain-type folk migrations", but by the introduction of these languages by ritual and political elites, which were emulated by large groups of people, a process which he calls "elite recruitment".

According to Parpola, local elites joined "small but powerful groups" of Indo-European speaking migrants. These migrants had an attractive social system and good weapons, and luxury goods which marked their status and power. Joining these groups was attractive for local leaders, since it strengthened their position, and gave them additional advantages. These new members were further incorporated by matrimonial alliances.

According to Joseph Salmons, language shift is facilitated by "dislocation" of language communities, in which the elite is taken over. According to Salmons, this change is facilitated by "systematic changes in community structure", in which a local community becomes incorporated in a larger social structure.

Genetics: ancient ancestry and multiple gene flows

The Indo-Aryan migrations form part of a complex genetic puzzle on the origin and spread of the various components of the Indian population, including various waves of admixture and language shift. Studies indicate north and south Indians share a common maternal ancestry. A series of studies show that the Indian subcontinent harbours two major ancestral components, namely the ''Ancestral North Indians'' (ANI) which is "genetically close to Middle Easterners, Central Asians, and Europeans", and the ''Ancestral South Indians'' (ASI) which is clearly distinct from ANI. These two groups mixed in India between 4,200 and 1,900 years ago (2200 BCE – 100 CE), after which a shift to endogamy took place, possibly by the enforcement of "social values and norms" during the Gupta Empire.

Moorjani et al. (2013) describe three scenarios regarding the bringing together of the two groups: migrations before the development of agriculture before 8,000–9,000 years before present (BP); migration of western Asian people together with the spread of agriculture, maybe up to 4,600 years BP; migrations of western Eurasians from 3,000 to 4,000 years BP.

While Reich notes that the onset of admixture coincides with the arrival of Indo-European language, according to Moorjani et al. (2013) these groups were present "unmixed" in India before the Indo-Aryan migrations. Gallego Romero et al. (2011) propose that the ANI component came from Iran and the Middle East, less than 10,000 years ago, while according to Lazaridis et al. (2016) ANI is a mix of "early farmers of western Iran" and "people of the Bronze Age Eurasian steppe". Several studies also show traces of later influxes of maternal genetic material and of paternal genetic material related to ANI and possibly the Indo-Europeans. While others have analysed the herditary distribution of Lactose intolerance, and specifically the presence of the -13910T Lactase persistence mutation, found in Europe and Central Asia, across South Asia.

Literary research: similarities, geography, and references to migration

The oldest known inscribed Indo-Iranian words, and particularly invocations of the Indo-Aryan deities, date to mid second millenia BCE, as loan words in Hurrian treaties of the Mitanni kingdom, of present day northern Syria.

The religious practices depicted in the ''Rigveda'' and those depicted in the ''Avesta'', the central religious text of Zoroastrianism, show similarities. Some of the references to the Sarasvati in the Rigveda refer to the Ghaggar-Hakra River,"Encyclopaedia of Ancient Indian Geography, Volume 2", by Subodh Kapoor, p.590 while the Afghan river Haraxvaiti/Harauvati Helmand is sometimes quoted as the locus of the early Rigvedic river."Discovering the Vedas: Origins, Mantras, Rituals, Insights", p. 7, by Frits Staal The Rigveda does not explicitly refer to an external homeland or to a migration, but later Vedic and Puranic texts do show the movement into the Gangetic plains. A number of Indologists and historians offering the Baudhayana Shrauta Sutra, verse 18.44:397.9, as explicit recorded evidence of a migration,Agarwal, Vishal: Is there Vedic evidence for the Indo-Aryan Immigration to India while others have criticised their interpretations, or the general reliability of Vedic texts, discounting the like of:

Ecological studies: widespread drought, urban collapse, and pastoral migrations

Climate change and drought may have triggered both the initial dispersal of Indo-European speakers, and the migration of Indo-Europeans from the steppes in south central Asia and India.

Around 4200–4100 BCE a climate change occurred, manifesting in colder winters in Europe. Steppe herders, archaic Proto-Indo-European speakers, spread into the lower Danube valley about 4200–4000 BCE, either causing or taking advantage of the collapse of Old Europe.

The Yamna horizon was an adaptation to a climate change which occurred between 3500 and 3000 BCE, in which the steppes became drier and cooler. Herds needed to be moved frequently to feed them sufficiently, and the use of wagons and horse-back riding made this possible, leading to "a new, more mobile form of pastoralism".

In the third millennium BCE widespread aridification led to water shortages and ecological changes in both the Eurasian steppes and the Indian subcontinent.Rajesh Kochhar (2017)
"The Aryan chromosome"
''The Indian Express'' On the steppes, humidification led to a change of vegetation, triggering "higher mobility and transition to nomadic cattle breeding". Water shortage also had a strong impact in the Indian subcontinent, "causing the collapse of sedentary urban cultures in south central Asia, Afghanistan, Iran, and India, and triggering large-scale migrations".

Development of the theory

Similarities between Sanskrit, Persian, Greek

In the 16th century, European visitors to India became aware of similarities between Indian and European languages and as early as 1653 Van Boxhorn had published a proposal for a proto-language ("Scythian") for Germanic, Romance, Greek, Baltic, Slavic, Celtic and Iranian.Roger Blenc
Archaeology and Language: methods and issues
In: ''A Companion To Archaeology''. J. Bintliff ed. 52–74. Oxford: Basil Blackwell, 2004.

In a memoir sent to the French Academy of Sciences in 1767 Gaston-Laurent Coeurdoux, a French Jesuit who spent all his life in India, had specifically demonstrated the existing analogy between Sanskrit and European languages.

In 1786 William Jones, a judge in the Supreme Court of Judicature at Fort William, Calcutta, linguist, and classics scholar, on studying Sanskrit, postulated, in his ''Third Anniversary Discourse '' to the Asiatic Society, a proto-language uniting Sanskrit, Persian, Greek, Latin, Gothic and Celtic languages, but in many ways his work was less accurate than his predecessors', as he erroneously included Egyptian, Japanese and Chinese in the Indo-European languages, while omitting Hindustani and Slavic:

Jones concluded that all these languages originated from the same source.

Homeland

Scholars assume a homeland either in central Asia or in Western Asia, and Sanskrit must in this case have reached India by a language transfer from west to east. In 19th century Indo-European studies, the language of the Rigveda was the most archaic Indo-European language known to scholars, indeed the only records of Indo-European that could reasonably claim to date to the Bronze Age. This primacy of Sanskrit inspired scholars such as Friedrich Schlegel, to assume that the locus of the proto-Indo-European homeland had been in India, with the other dialects spread to the west by historical migration.

With the 20th-century discovery of Bronze-Age attestations of Indo-European (Anatolian, Mycenaean Greek), Vedic Sanskrit lost its special status as the most archaic Indo-European language known."Tense and Aspect in Indo-European Languages", by John Hewson, Page 229

Aryan "race"

In the 1850s Max Müller introduced the notion of two Aryan races, a western and an eastern one, who migrated from the Caucasus into Europe and India respectively. Müller dichotomized the two groups, ascribing greater prominence and value to the western branch. Nevertheless, this "eastern branch of the Aryan race was more powerful than the indigenous eastern natives, who were easy to conquer".

Herbert Hope Risley expanded on Müller's two-race Indo-European speaking Aryan invasion theory, concluding that the caste system was a remnant of the Indo-Aryans domination of the native Dravidians, with observable variations in phenotypes between hereditary, race based, castes. Thomas Trautmann explains that Risley "found a direct relation between the proportion of Aryan blood and the nasal index, along a gradient from the highest castes to the lowest. This assimilation of caste to race proved very influential."

Müller's work contributed to the developing interest in Aryan culture, which often set Indo-European ('Aryan') traditions in opposition to Semitic religions. He was "deeply saddened by the fact that these classifications later came to be expressed in racist terms", as this was far from his intention. For Müller the discovery of common Indian and European ancestry was a powerful argument against racism, arguing that "an ethnologist who speaks of Aryan race, Aryan blood, Aryan eyes and hair, is as great a sinner as a linguist who speaks of a dolichocephalic dictionary or a brachycephalic grammar" and that "the blackest Hindus represent an earlier stage of Aryan speech and thought than the fairest Scandinavians". In his later work, Max Müller took great care to limit the use of the term "Aryan" to a strictly linguistic one.

"Aryan invasion"

The excavation of the Harappa, Mohenjo-daro sites of the Indus Valley civilisation (IVC) in the 1920, showed that northern India already had an advanced culture when the Indo-Aryans migrated into the area. The theory changed from a migration of advanced Aryans towards a primitive aboriginal population, to a migration of nomadic people into an advanced urban civilization, comparable to the Germanic migrations during the Fall of the Western Roman Empire, or the Kassite invasion of Babylonia.

This possibility was for a short time seen as a hostile invasion into northern India. The decline of the Indus Valley civilisation at precisely the period in history in which the Indo-Aryan migrations probably took place, seemed to provide independent support of such an invasion. This argument was proposed by the mid-20th century archaeologist Mortimer Wheeler, who interpreted the presence of many unburied corpses found in the top levels of Mohenjo-daro as the victims of conquest wars, and who famously stated that the god "Indra stands accused" of the destruction of the Civilisation.

This position was discarded after finding no evidence of wars. The skeletons were found to be hasty interments, not massacred victims. Wheeler himself also nuanced this interpretation in later publications, stating "This is a possibility, but it can't be proven, and it may not be correct." Wheeler further notes that the unburied corpses may indicate an event in the final phase of human occupation of Mohenjo-Daro, and that thereafter the place was uninhabited, but that the decay of Mohenjo-Daro has to be ascribed to structural causes such as salinisation.

Nevertheless, although 'invasion' was discredited, critics of the Indo-Aryan Migration theory continue to present the theory as an "Aryan Invasion Theory", presenting it as a racist and colonialist discourse:

Aryan migration

In the later 20th century, ideas were refined along with data accrual, and migration and acculturation were seen as the methods whereby Indo-Aryans and their language and culture spread into northwest India around 1500 BCE. The term "invasion" is only being used nowadays by opponents of the Indo-Aryan Migration theory. Michael Witzel:

The changed approach was in line with newly developed thinking about language transfer in general, such as the migration of the Greeks into Greece (between 2100 and 1600 BCE) and their adoption of a syllabic script, Linear B, from the pre-existing Linear A, with the purpose of writing Mycenaean Greek, or the Indo-Europeanization of Western Europe (in stages between 2200 and 1300 BCE).

Future directions

Mallory notes that with the development and the growing sophistication of the knowledge on the Indo-European migrations and their purported homeland, new questions arise, and that "it is evident that we still have a very long way to go." One of those questions is the origin of the shared agricultural vocabulary, and the earliest dates for agriculturalism in areas settled by the Indo-Europeans. Those dates seem to be too late to account for the shared vocabulary, and raise the question what their origin is.

Linguistics: relationships between languages

Linguistic research traces the connections between the various Indo-European languages, and reconstructs proto-Indo-European. Accumulated linguistic evidence points to the Indo-Aryan languages as intrusive into the Indian subcontinent, some time in the 2nd millennium BCE. The language of the Rigveda, the earliest stratum of Vedic Sanskrit, is assigned to about 1500–1200 BCE.

Comparative method

Connections between languages can be traced because the processes that change languages are not random, but follow strict patterns. Especially sound shifts, the changing of vowels and consonants, are important, although grammar (especially morphology) and the lexicon (vocabulary) may also be significant. Historical-comparative linguistics thus makes it possible to see great similarities between languages which at first sight might seem very different.

Linguistics use the comparative method to study the development of languages by performing a feature-by-feature comparison of two or more languages with common descent from a shared ancestor, as opposed to the method of internal reconstruction, which analyses the internal development of a single language over time. Ordinarily both methods are used together to reconstruct prehistoric phases of languages, to fill in gaps in the historical record of a language, to discover the development of phonological, morphological, and other linguistic systems, and to confirm or refute hypothesized relationships between languages.

The comparative method aims to prove that two or more historically attested languages are descended from a single proto-language by comparing lists of cognate terms. From them, regular sound correspondences between the languages are established, and a sequence of regular sound changes can then be postulated, which allows the proto-language to be reconstructed. Relation is deemed certain only if at least a partial reconstruction of the common ancestor is feasible, and if regular sound correspondences can be established with chance similarities ruled out.

The comparative method was developed over the 19th century. Key contributions were made by the Danish scholars Rasmus Rask and Karl Verner and the German scholar Jacob Grimm. The first linguist to offer reconstructed forms from a proto-language was August Schleicher, in his ''Compendium der vergleichenden Grammatik der indogermanischen Sprachen'', originally published in 1861.

Proto-Indo-European

Proto-Indo-European (PIE) is the linguistic reconstruction of the common ancestor of the Indo-European languages. August Schleicher's 1861 reconstruction of PIE was the first proposed proto-language to be accepted by modern linguists. More work has gone into reconstructing it than any other proto-language, and it is by far the best understood among all proto-languages of its age. During the 19th century, the vast majority of linguistic work was devoted to reconstruction of Proto-Indo-European or its daughter proto-languages such as Proto-Germanic, and most of the current techniques of linguistic reconstruction in historical linguistics (e.g., the comparative method and the method of internal reconstruction) were developed as a result.

PIE must have been spoken as a single language or a group of related dialects (before divergence began), though estimates of when this was by different authorities can vary massively, from the 7th millennium BCE to the second. A number of hypotheses have been proposed for the origin and spread of the language, the most popular among linguists being the Kurgan hypothesis, which postulates an origin in the Pontic–Caspian steppe of Eastern Europe in the 5th or 4th millennia BCE. Features of the culture of the speakers of PIE, known as Proto-Indo-Europeans, have also been reconstructed based on the shared vocabulary of the early attested Indo-European languages.

As mentioned above, the existence of PIE was first postulated in the 18th century by Sir William Jones, who observed the similarities between Sanskrit, Ancient Greek, and Latin. By the early 20th century, well-defined descriptions of PIE had been developed that are still accepted today (with some refinements). The largest developments of the 20th century were the discovery of the Anatolian and Tocharian languages and the acceptance of the laryngeal theory. The Anatolian languages have also spurred a major re-evaluation of theories concerning the development of various shared Indo-European language features and the extent to which these features were present in PIE itself. Relationships to other language families, including the Uralic languages, have been proposed but remain controversial.

PIE is thought to have had a complex system of morphology that included inflectional suffixes as well as ablaut (vowel alterations, as preserved in English ''sing, sang, sung''). Nouns and verbs had complex systems of declension and conjugation respectively.

Arguments against an Indian origin of proto-Indo-European

Diversity

According to the linguistic center of gravity principle, the most likely point of origin of a language family is in the area of its greatest diversity. By this criterion, Northern India, home to only a single branch of the Indo-European language family (i.e., Indo-Aryan), is an exceedingly unlikely candidate for the Indo-European homeland, compared to Central-Eastern Europe, for example, which is home to the Italic, Venetic, Illyrian, Albanian, Germanic, Baltic, Slavic, Thracian and Greek branches of Indo-European.

Both mainstream Urheimat solutions locate the Proto-Indo-European homeland in the vicinity of the Black Sea.

Dialectal variation

It has been recognized since the mid-19th century, beginning with Schmidt and Schuchardt, that a binary tree model cannot capture all linguistic alignments; certain areal features cut across language groups and are better explained through a model treating linguistic change like waves rippling out through a pond. This is true of the Indo-European languages as well. Various features originated and spread while Proto-Indo-European was still a dialect continuum. These features sometimes cut across sub-families: for instance, the instrumental, dative and ablative plurals in Germanic and Balto-Slavic feature endings beginning with -m-, rather than the usual -*bh-, e.g. Gothic dative plural '' sunum'' 'to the sons' and Old Church Slavonic instrumental plural '' synъ-mi'' 'with sons', despite the fact that the Germanic languages are centum, while Balto-Slavic languages are satem.

The strong correspondence between the dialectal relationships of the Indo-European languages and their actual geographical arrangement in their earliest attested forms makes an Indian origin, as suggested by the Out of India Theory, unlikely.Hock (1996), "Out of India? The linguistic evidence", in .

Substrate influence

Already in the 1870s the Neogrammarians realised that the Greek/Latin vocalism couldn't be explained on the basis of the Sanskrit one, and therefore must be more original. The Indo-Iranian and Uralic languages influenced each other, with the Finno-Ugric languages containing Indo-European loan words. A telling example is the Finnish word ''vasara'', "hammer", which is related to ''vajra'', the weapon of Indra. Since the Finno-Ugric homeland was located in the northern forest zone in northern Europe, the contacts must have taken place – in line with the placement of the proto-Indo-European homeland at the Pontic-Caspian steppes – between the Black Sea and the Caspian Sea.

Dravidian and other South Asian languages share with Indo-Aryan a number of syntactical and morphological features that are alien to other Indo-European languages, including even its closest relative, Old Iranian. Phonologically, there is the introduction of retroflexes, which alternate with dentals in Indo-Aryan; morphologically there are the gerunds; and syntactically there is the use of a quotative marker (''iti''). These are taken as evidence of substratum influence.

It has been argued that Dravidian influenced Indic through "shift", whereby native Dravidian speakers learned and adopted Indic languages. The presence of Dravidian structural features in Old Indo-Aryan is thus plausibly explained, that the majority of early Old Indo-Aryan speakers had a Dravidian mother tongue which they gradually abandoned. Even though the innovative traits in Indic could be explained by multiple internal explanations, early Dravidian influence is the only explanation that can account for all of the innovations at once – it becomes a question of explanatory parsimony; moreover, early Dravidian influence accounts for several of the innovative traits in Indic better than any internal explanation that has been proposed.

A pre-Indo-European linguistic substratum in the Indian subcontinent would be a good reason to exclude India as a potential Indo-European homeland. However, several linguists, all of whom accept the external origin of the Aryan languages on other grounds, are still open to considering the evidence as internal developments rather than the result of substrate influences, or as adstratum effects.

Archaeology: migrations from the steppe Urheimat

The Sintashta, Andronovo, Bactria-Margiana and Yaz cultures have been associated with Indo-Iranian migrations in Central Asia. The Gandhara Grave, Cemetery H, Copper Hoard and Painted Grey Ware cultures are candidates for subsequent cultures within south India associated with Indo-Aryan movements. The decline of the Indus Valley Civilisation predates the Indo-Aryan migrations, but archeological data show a cultural continuity in the archeological record. Together with the presence of Dravidian loanwords in the Rigveda, this argues in favor of an interaction between post-Harappan and Indo-Aryan cultures.

Stages of migrations

About 6,000 years ago the Indo-Europeans started to spread out from their proto-Indo-European homeland in Central Eurasia, between the southern Ural Mountains, the North Caucasus, and the Black Sea. About 4,000 years ago Indo-European speaking peoples started to migrate out of the Eurasian steppes.

Diffusion from the "Urheimat"

Scholars regard the middle Volga, which was the location of the Samara culture (late 6th and early 5th millennium BCE), and the Yamna culture, to be the "Urheimat" of the Indo-Europeans, as described by the Kurgan hypothesis. From this "Urheimat", Indo-European languages spread throughout the Eurasian steppes between c. 4,500 and 2,500 BCE, forming the Yamna culture.

Sequence of migrations

David Anthony gives an elaborate overview of the sequence of migrations.

The oldest attested Indo-European language is Hittite, which belongs to the oldest written Indo-European languages, the Anatolian branch. Although the Hittites are placed in the 2nd millennium BCE, the Anatolian branch seems to predate Proto-Indo-European, and may have developed from an older Pre-Proto-Indo-European ancestor. If it separated from Proto-Indo-European, it is likely to have done so between 4500 and 3500 BCE.

A migration of archaic Proto-Indo-European speaking steppe herders into the lower Danube valley took place about 4200–4000 BCE, either causing or taking advantage of the collapse of Old Europe.

According to Mallory and Adams, migrations southward founded the Maykop culture (c. 3500–2500 BCE), and eastward the Afanasevo culture (c. 3500–2500 BCE), which developed into the Tocharians (c. 3700–3300 BCE).

According to Anthony, between 3100 and 2800/2600 BCE, a real folk migration of Proto-Indo-European speakers from the Yamna-culture took place toward the west, into the Danube Valley. These migrations probably split off Pre-Italic, Pre-Celtic and Pre-Germanic from Proto-Indo-European. According to Anthony, this was followed by a movement north, which split away Baltic-Slavic c. 2800 BCE. Pre-Armenian split off at the same time. According to Parpola, this migration is related to the appearance of Indo-European speakers from Europe in Anatolia, and the appearance of Hittite.

The Corded Ware culture in Middle Europe ( 2900–2450/2350 cal. BCE), has been associated with some of the languages in the Indo-European family. According to Haak et al. (2015) a massive migration took place from the Eurasian steppes to Central Europe. This migration is closely associated with the Corded Ware culture.Mac-Planck Gesellschaft, ''A massive migration from the steppe brought Indo-European languages to Europe''
/ref>Ewen Callaway (12 February 2015), ''European languages linked to migration from the east. Large ancient-DNA study uncovers population that moved westwards 4,500 years ago.'', Nature
/ref>

The Indo-Iranian language and culture emerged in the Sintashta culture (c. 2050–1900 BCE), where the chariot was invented. Allentoft et al. (2015) found close autosomal genetic relationship between peoples of Corded Ware culture and Sintashta culture, which "suggests similar genetic sources of the two", and may imply that "the Sintashta derives directly from an eastward migration of Corded Ware peoples".

The Indo-Iranian language and culture was further developed in the Andronovo culture (c. 2000–1450 BCE), and influenced by the Bactria–Margiana Archaeological Complex (c. 2250–1700 BCE). The Indo-Aryans split off sometime around 2000–1600 BCE from the Iranians, after which Indo-Aryan groups are thought to have moved to the Levant (Mitanni), the northern Indian subcontinent (Vedic people, c. 1500 BCE), and China (Wusun