Treaty of Aigun

The Treaty of Aigun, signed in May 1858 between the Russian Empire and Qing China, transferred the left, or northern, bank of the Amur River from Chinese to Russian control while leaving the Ussuri region to the east under joint administration pending further settlement. The agreement reversed the boundary that had stood since the 1689 Treaty of Nerchinsk and was concluded while the Qing state was weakened by internal rebellion and the Second Opium War. Its terms were extended two years later when the Convention of Peking ceded the Ussuri region outright to Russia.