century, Russia-China relations were formalized in the 1689 Treaty of Nerchinsk, which established the Argun River as the China–Russia border. However, prior to the Amur Annexation of Outer Manchurian territory, China's border extended further to include the so-called Sixty-Four Villages East of the River in present-day Amur Oblast, southern Khabarovsk, and all of Primorsky Krai. Although the subsequent Amur Annexation fixed the eastern Sino-Russian border at the Amur, it would only be at the 1991 Sino-Soviet Border Agreement when all Sino-Soviet border conflicts would be resolved. References Rivers of Inner Mongolia Rivers of Zabaykalsky Krai Border rivers China–Russia border International rivers of Asia