A-ERH-CHIN MOUNTAINS

also called Altyn Tagh, Chinese (Wade-Giles) A-erh-chin Shan, or (Pinyin) Altun Shan, mountain range in southern Uighur Autonomous Region of Sinkiang, China. Branching off from the Kunlun Mountains, the range runs from southwest to northeast to form the boundary between the Tarim Basin to the north and the minor basin of Lake A-ya-k'o-k'u-mu and the Tsaidam Basin areas of interior drainage to the south. The range falls into three divisions. The southwest section, bordering the Kunlun, is extremely rugged and complex; some ranges and peaks rise to heights of more than 20,000 feet (6,100 m) and are covered with perpetual snows. The central portion, forming the border of the western Tsaidam Basin, is lower, averaging about 13,000 feet (4,000 m) in height, and is much narrower. The eastern section, in which the range joins the Nan Mountains, is again higher, with peaks of 16,500 feet (5,000 m); it is structurally more complicated, consisting of a series of short ranges, the axes of which gradually adapt to the main northwest-to-southeast axis of the Nan system. There are very few rivers, because the area is one of extreme aridity, particularly in its central section. In the west various small streams run off into the Takla Makan Desert in the north, into Lake A-ya-k'o-k'u-mu to the south, or into the western Tsaidam Basin. The main pass is the Tang-chin Pass at the eastern end, which is crossed by a motor road between eastern Sinkiang (via Kansu province), the Tsaidam Basin, and the Tibet Autonomous Region (via Tsinghai province).