Juyan Lake
42°17′N 100°37′E / 42.283°N 100.617°E
The Juyan Lake (Chinese: 居延海; Wade–Giles: Chüyen Hai, Mongolian: Sogo Nuur) is an endorheic lake in the Badain Jaran Desert. It is located in the western part of Inner Mongolia, in Ejin Banner of the Alxa League, near the border with Mongolia. It originally referred to two lakes, the western of which was called Gashuun Nuur in Mongolian (Chinese: 嘎顺淖尔 Gāshùn nào'ěr or 嘎顺诺尔 Gāshùn nuò'ěr). Through the process of desertification, Gashuun Nuur had an area of 267 km2 (103 sq mi) in 1958, 213 km2 (82 sq mi) in 1960, and dried up completely in 1961. The eastern lake followed in 1992, but reappeared in 2005. As of August 2012, the area of the lake is 38 km2 (15 sq mi).
The Juyan Lake Wetland is the inland delta of the Ejin River, also known as the Black River. It covers an area of about 10,000 square kilometres (3,900 sq mi). The Juyan Lake constitutes the only remaining of three former terminal lakes.
The wider region, having been called Juyan since ancient times, was a vital area of Chinese dynasties from the Han all the way to at least the Yuan.