TSAIDAM  , or more correctly TsADUM, a depression, or self-contained 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 perfectlyunknown, 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 border-land, 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 .