The Treaty of Turkmenchay (Туркманчайский договор; Persian: عهدنامه ترکمنچای) was a treaty negotiated in Turkmenchay by which the Persian Empire, more commonly known today as Iran, recognized Russian suzerainty over the Erivan khanate, Nakhchivan khanate and the remainder of the Talysh khanate, establishing the Aras River as the common boundary between both empires, after its defeat in 1828 at the end of the Russo-Persian War, 1826-1828. The treaty was signed on February 21, 1828 by Haj Mirza Abol-hasan Khan and Asef o-dowleh, chancellor of Fath Ali Shah on behalf of Persia, and General Ivan Paskievich representing Imperial Russia. As was the case for the Treaty of Gulistan, Persia was forced to sign the treaty by Russia, as it had no alternative after crown prince Abbas Mirza's defeat. The Russian general had threatened Fath Ali Shah to conquer Tehran in five days unless the treaty was signed.
By this treaty:
In 1812 Russia ended a war with Turkey and went on the offensive against Iran. This led to the treaty of Gulistan in 1813, which gave Russia control over large territories that hitherto had been at least nominally Iranian, and moreover a say in Iranian succession politics. The whole of Daghestan and Georgia, including Mingrelia and Abkhazia were formally ceded to Russia, as well as eight Azeri Khanates (Karabakh, Ganja, Sheki, Kuba, Shirvan, Talysh, Baku, and Derbent). However as we have seen the Persians soon challenged Russia’s rule in the area, resulting in a military disaster. Iran lost control over the whole of Azerbaijan, and with the Turkemenchai settlement of 1828 Russia threatened to establish its control over Azerbaijan unless Iran paid a war indemnity. The British helped the Iranians with the matter, but the fact remained that Russian troops had marched as far as south of Tabriz. Although certain areas (including Tabriz) were returned to Iran, Russia was in fact at the peak of its territorial expansion.
According to Cambridge History of Iran:
"Even when rulers on the plateau lacked the means to effect suzerainty beyond the Aras, the neighboring Khanates were still regarded as Iranian dependencies. Naturally, it was those Khanates located closes to the province of Azarbaijan which most frequently experienced attempts to re-impose Iranian suzerainty: the Khanates of Erivan, Nakhchivan and Qarabagh across the Aras, and the cis-Aras Khanate of Talish, with its administrative headquarters located at Lankaran and therefore very vulnerable to pressure, either from the direction of Tabriz or Rasht. Beyond the Khanate of Qarabagh, the Khan of Ganja and the Vali of Gurjistan (ruler of the Kartli-Kakheti kingdom of south-east Georgia), although less accessible for purposes of coercion, were also regarded as the Shah's vassals, as were the Khans of Shakki and Shirvan, north of the Kura river. The contacts between Iran and the Khanates of Baku and Qubba, however, were more tenuous and consisted mainly of maritime commercial links with Anzali and Rasht. The effectiveness of these somewhat haphazard assertions of suzerainty depended on the ability of a particular Shah to make his will felt, and the determination of the local khans to evade obligations they regarded as onerous.
Iran sees this and the preceding Treaty of Gulistan as the most humiliating treaties signed in the country's millennia-old history. The treaty is the reason many Iranians consider Fath Ali Shah to be one of Iran's most incompetent rulers.