River in E Asia. Formed by the Argun and
Shilka rivers, the Amur enters the Sea of
Okhotsk. At its mouth at Nikolaevsk it is 16
km/10 mi wide. For much of its course of over
4,400 km/2,730 mi it forms, together with its
tributary, the Ussuri, the boundary between
the USSR and China. Under the treaties of
Aigun (1858) and Peking (1860), 984,200 sq
km/380,000 sq mi of territory N and E of the
two rivers were ceded by China to the tsarist
government. From 1963 China raised the
question of its return and there have been
border clashes.