The Treaty of Saint Petersburg (1881), also known as Treaty of Ili, was the treaty between the Russian Empire and the Qing dynasty that was signed in Saint Petersburg, Russia, on 24 February [O.S. 12 February] 1881.
It provided for returning to China the eastern part of the Ili Basin region, also known as Zhetysu, which had been occupied by Russia since 1871 during the Dungan Revolt.
During the Russian conquest of Turkestan, Russia gained control of eastern Kazakhstan up to the current Chinese border. During the Dungan Revolt, China lost control of much of its western territory, and power passed to various factions. In 1871, Russia occupied the Ili territory. There was talk of permanent annexation, but Saint Petersburg declared that it was occupying the territory to protect its citizens. Chinese authority in Xinjiang was re-established by 1877.