evidence: The Amur River or Heilong Jiang is the world’s tenth longest river, forming the border between the Russian Far East and Northeastern China (Inner Manchuria). The largest fish species in the Amur is the kaluga, attaining a length as great as 5.6 metres. [...] In many historical references these two geopolitical entities are known as Outer Manchuria (Russian Manchuria) and Inner Manchuria, respectively. The Chinese province of Heilongjiang on the south bank of the river is named after it, as is the Russian Amur Oblast on the north bank. The name Black River (sahaliyan ula) was used by the Manchu and the Ta-tsing Empire who regarded this river as sacred. [...] The Amur region remained a relative backwater of the Ta-tsing Empire for the next century and a half, with Aigun being practically the only major town on the river. Russians re-appeared on the river in the mid-19th century, forcing the Manchus to yield all lands north of the river to the Russian Empire by the Treaty of Aigun (1858). Lands east of the Ussury and the lower Amur were acquired by Russia as well, by the Convention of Peking (1860).