Iran–Türkiye border

Three centuries of vagueness

A boundary between the Ottoman and Persian empires, in roughly its present place, was laid down in 1639 from the Aras River to the Persian Gulf. It divided the Kurds, who had lived in the uplands north of Mesopotamia for at least 3,000 years. Little was done to put it into effect for two centuries.^[1]

Under British and Russian pressure, the Treaty of Erzurum of 1847 defined the limits vaguely and set up a four-power commission. After surveys in 1848–52 and years of map-making, it produced in 1869 the “Carte Identique”, beautifully drawn but highly inaccurate, which showed a border zone 25 miles wide within which the line lay somewhere. The Treaty of Berlin in 1878 gave the Qotur area to Persia.^[1]

A commission set up in 1911 redefined most of the line, recorded in the Constantinople Protocol of November 1913, and by October 1914 all but about 40 miles near Qotur had been marked. The creation of British-mandated Iraq in 1920 then cut the Turkish–Persian border to about a quarter of its former length.^[1]

Settled at last

After a Kurdish revolt against the Turkish government in 1925, the two countries agreed at Ankara in 1929 to review their border. The Tehran agreement of 23 January 1932 made three small swaps: the eastern flank of Little Ararat to Turkey, which had seen Kurdish tribes organise uprisings there, and areas at Qotur and Bajirge to Iran. A final rectification followed in May 1937. In 1964 the US Geographer found no major disputes and no latent claims on either side.^[1]

A 1955 protocol shared the waters of the Kara Su and Sarı Su, two streams that rise in Turkey and flow into or along Iran, giving both countries equal rights to the Kara Su and Iran a guaranteed minimum flow of the Sarı Su.^[1]

“a boundary which for three centuries was an almost constant source of dispute”^[1]

Highlands, wall and crossings

From the lava plains around Ararat the line follows mountain crests, mostly along the watershed between streams running west to Lake Van and the Tigris and east to Lake Urmia and the Aras; the land rises in places above 10,000 feet. Kurds live on both sides, many of them once semi-nomadic herders whose seasonal moves at times crossed the border. In 1964 the only major highway across it ran between Doğubayazıt and Maku.^[1]

By 2021 about 140 km of the border was protected by a concrete wall topped with barbed wire, yet by 16 June that year Turkey’s migration authorities had stopped 53,176 migrants, many of them Afghans and Pakistanis fleeing war and Iranians seeking work.^[2]

When US and Israeli strikes closed Iran’s airspace in March 2026, the Kapıköy crossing near Van became one of the few routes connecting Iranians to the rest of the world; about 2,000 people entered Turkey from Iran there on a single day, though AP saw no major exodus.^[3]