Caption:
The Black River (also known as the Da River, sông Ðà in Vietnamese and Lixian River in China) is a river located in China and northwestern Vietnam. Its source is in Yunnan Province of China. It runs through the Vietnamese provinces of Lai Châu (where it forms part of the border with Ði?n Biên Province), Son La and Hòa Bình. It is the most important tributary of the Red River, which it joins in Tam Nong District near Vi?t Trì in Phú Th? Province. It also forms part of the border between Phú Th? Province and Hanoi (previously the border with Hà Tây Province). The rivers total length is 910 km, around 400 km in China and 527 km in Vietnam.