The Tumen River (圖們江, Tumenjiang) is located in Northeast Asia.
It forms the border between China and North Korea in the upper reaches and between North Korea and Russia at the mouth.
The Tumen River originates in the Changbai Mountains and flows 521 km long into the Sea of Japan.
... but the southern part of the island was held by the Japanese until 1875, when they ceded it to Russia. By the Treaty of Portsmouth (U.S.A.) of 1905 the southern part of ...