Tsaidam, or more correctly TsADUM, a depression, or selfcontained shallow basin in the N.E. of Tibet, crossed by 37° N. and stretching from 92° to 97°. It is separated from the high plateau of Tibet by the Burkhan-Buddha range, and on the N.E. it is bounded by the eastward continuation of the Astintagh ranges, which there consist of four, namely, the lower and upper ranges, and a subsidiary chain flanking the lower range on the north and another subsidiary chain flanking the upper range on the south (see KuEN-LuN).
The valleys which divide the east ranges of the Kuen-Lun system terminate, or rather merge in, the sandy desert basin of Tsaidam; amongst them the Kakir valley between the upper Astin-tagh and the Akato-tagh and the Kum-kol valley between the Kalta-alagan and the range I. of the Arka-tagh (see Kuen-Lun). Tsaidam lies at an altitude of 11,400 ft. or about 3000 ft. lower than the Kumkol lakes, and receives from the valley in which they lie the river Chulak-akkan or Tsagan tokhoy, which rises probably on the north slope of the Shapka-monomakha Mountain, one of the culminating summits in the region north of the Arka-tagh range. "It is very possible that the north-west of Tsaidam, which is perfectly unknown, is broken up into several separate basins. The south-east part of the same great expanse also appears to consist of several smaller basins rather than of one single great basin, each possessing its own salt lake; but then these smaller basins are undoubtedly separated from one another by remarkably low and insignificant thresholds or swellings." 1 The north-east part of the basin consists of a network of basins, which admit of being grouped in four divisions-Sartang or Serteng, Makhai, Tsadam or Tsaidam, and Kurlyk or Tosun. The characteristic feature of each of these is that which is found in so many of the valleys of the Tibetan borderland, namely, a pair of linked lakes, one containing salt water and the other fresh water. The only inhabitants of Tsaidam are Mongols -Sartang Mongols in the north and Tajinur Mongols in the south. The south-east part of the region is drained by the Holuzun-nor or Bain-gol, an affluent of the upper Hwang-ho or Yellow River of China. The Sartang basin is drained by the Khalting-gol and its tributary the Holuin-gol, which rise in the Humboldt and Ritter Mountains and empty into the lake of Sukhain-nor.
