The

Azerbaijan Azerbaijan, officially the Republic of Azerbaijan, is a Boundaries between the continents, transcontinental and landlocked country at the boundary of West Asia and Eastern Europe. It is a part of the South Caucasus region and is bounded by ...

–

Iran Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the nort ...

border (, ) is 689 km (428 mi) in length and consists of two non-contiguous sections separated by the 44-km long Armenia–Iran border.

Description

Western (Nakchivan) section

The border starts in the north-west at the tripoint with Turkey on the

Aras river The Aras is a transboundary river in the Caucasus. It rises in eastern Turkey and flows along the borders between Turkey and Armenia, between Turkey and the Nakhchivan exclave of Azerbaijan, between Iran and both Azerbaijan and Armenia, and, fin ...

, continuing along this river south-eastwards, through the Aras reservoir (created by the Aras Dam) and down to the western Armenian tripoint.

Eastern section

The border starts in the west at the eastern Armenian tripoint on the Aras river, and then follows this river as it flows north-eastwards. The border leaves the river at a point south of Bəhramtəpə, turning sharply south-eastwards and proceeding across the Mugan plain to the Bolgarchay river. The border then follows this river south forming a broad S-shape. The river ends near Yardımlı, with the border then curving south-eastwards, proceeding overland in that direction through the Talysh Mountains, then turning east along the Astarachay river, following its course all the way to the

Caspian Sea The Caspian Sea is the world's largest inland body of water, described as the List of lakes by area, world's largest lake and usually referred to as a full-fledged sea. An endorheic basin, it lies between Europe and Asia: east of the Caucasus, ...

History

During the 19th century the Caucasus region was contested between the declining

Ottoman Empire The Ottoman Empire (), also called the Turkish Empire, was an empire, imperial realm that controlled much of Southeast Europe, West Asia, and North Africa from the 14th to early 20th centuries; it also controlled parts of southeastern Centr ...

Persia Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the nort ...

and

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

, which was expanding southwards. By the Russo-Persian War (1804–1813) and the subsequent

Treaty of Gulistan The Treaty of Gulistan (also spelled Golestan: ; ) was a peace treaty concluded between the Russian Empire and Qajar Iran on 24 October 1813 in the village of Gülüstan, Goranboy, Gulistan (now in Goranboy District, the Goranboy District of Azerb ...

, Russia acquired the bulk of what is now Azerbaijan and parts of Armenia; a border was drawn which is the modern border between Iran and Azerbaijan (excluding the Nakhichevan section) and Iran and Armenia. Following the

Russo-Persian War (1826–1828) The Russo-Persian War of 1826–1828 was the last major military conflict between the Russian Empire and Qajar Iran, which was fought over territorial disputes in the South Caucasus region. Initiated by Russian expansionist aims and intensifie ...

and the

Treaty of Turkmenchay The Treaty of Turkmenchay (; ) was an agreement between Qajar Iran and the Russian Empire, which concluded the Russo-Persian War (1826–1828). It was second of the series of treaties (the first was the 1813 Treaty of Gulistan and the last, the ...

Persia was forced to cede Nakhchivan and the rest of Armenia to Russia; the Aras was extended as the border up to the Ottoman tripoint, thus finalising what would become the Azerbaijan–Iran border. During the

First World War World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

Russian Communists staged a successful

revolution In political science, a revolution (, 'a turn around') is a rapid, fundamental transformation of a society's class, state, ethnic or religious structures. According to sociologist Jack Goldstone, all revolutions contain "a common set of elements ...

in 1917, whilst the peoples of the southern Caucasus had declared the Transcaucasian Democratic Federative Republic in 1918. Internal disagreements led to

Georgia Georgia most commonly refers to: * Georgia (country), a country in the South Caucasus * Georgia (U.S. state), a state in the southeastern United States Georgia may also refer to: People and fictional characters * Georgia (name), a list of pe ...

leaving the federation in May 1918, followed shortly thereafter by

Armenia Armenia, officially the Republic of Armenia, is a landlocked country in the Armenian Highlands of West Asia. It is a part of the Caucasus region and is bordered by Turkey to the west, Georgia (country), Georgia to the north and Azerbaijan to ...

and

. By its very name the newly independent Azerbaijan caused tensions with Persia, as it seemed to imply a claim to Iran's Azerbaijan region. In 1920 Russia's

Red Army The Workers' and Peasants' Red Army, often shortened to the Red Army, was the army and air force of the Russian Soviet Republic and, from 1922, the Soviet Union. The army was established in January 1918 by a decree of the Council of People ...

invaded Azerbaijan and Armenia, ending the independence of both, followed shortly thereafter by Georgia. All three states were incorporated into the Transcaucasian SFSR within the

USSR The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

, before being separated in 1936. A Soviet-backed separatist state in Iranian Azerbaijan was established 1945 but was soon quashed by Iranian forces. An Iran–USSR border convention in 1954 made some minor adjustments along the frontier in the Mugan plain and near Deman and Namin, to Iran's benefit. On-the-ground demarcation then followed, with a final agreement being agreed upon in 1957. In 1970 some further adjustments were made to the Nakhchivan section of the border following the creation of the Aras dam. Following the collapse of the USSR in 1991 Azerbaijan gained independence and inherited its section of the Iran–USSR border. Iran quickly recognised the new state, though relations cooled over Iranian fears of Azerbaijan's potential claims to its territory as part of a ' Greater Azerbaijan', with Iran championing Armenia in the

First Nagorno-Karabakh War The First Nagorno-Karabakh War was an ethnic conflict, ethnic and territorial conflict that took place from February 1988 to May 1994, in the enclave of Nagorno-Karabakh in southwestern Azerbaijan, between the majority ethnic Armenians of Nag ...

.James P. Nichol. ''Diplomacy in the Former Soviet Republics'', Praeger/Greenwood, 1995, , p. 150 Following the war Armenia was left in control of the westernmost section of the 'mainland' Azerbaijan–Iran border. Relations between Iran and Azerbaijan have improved somewhat since the accession of

Hassan Rouhani Hassan Rouhani (; born Hassan Fereydoun, 12 November 1948) is an Iranian peoples, Iranian politician who served as the seventh president of Iran from 2013 to 2021. He is also a sharia lawyer ("Wakil"), academic, former diplomat and Islamic cl ...

in Iran. During the

2020 Nagorno-Karabakh War The Second Nagorno-Karabakh War was an armed conflict in 2020 that took place in the disputed region of Nagorno-Karabakh and the surrounding occupied territories. It was a major escalation of an unresolved conflict over the region, involvi ...

, Azerbaijan gained complete control of the western section of the border with Iran within one month from the self-proclaimed

Republic of Artsakh Artsakh ( ), officially the Republic of Artsakh or the Republic of Nagorno-Karabakh ( ), was a breakaway state in the South Caucasus whose territory was internationally recognised as part of Azerbaijan. Between 1991 and 2023, Artsakh cont ...

, ultimately restoring Azerbaijani control over the border.

Border crossings

There are crossings between 'mainland' Azerbaijan and Iran at Bilasuvar and Astara. Crossings between Iran and Nakchivan are at Jolfa/Julfa and Poldasht–Shahtakhti.

References