[10] It is one of the many saltwater lakes in the endorheic Qaidam Basin,[6] bound by the Qilian Mountains to the north, the Altun to the west, and the Kunlun to the south.

[7] Its area is thus variable by season and year,[13] usually 184–334 km2 (71–129 sq mi) but increasing in the wetter winter and spring and decreasing through the summer and fall.

Although the northern springs contribute much less volume, their waters carry far greater concentrations of solutes and are important to the chemical composition of the lake.

[16] Tectonic activity also varied sedimentation in the lake by shifting its tributaries and basins, although it remained in the Qarhan Playa during this period.

[17] At around 30,000 years ago, this great freshwater lake spread over at least 25,000 km2 (9,700 sq mi) with a surface 50–60 m (160–200 ft) above the present levels of its successors.

[9] The area's potassium deposits were accidentally discovered in 1957[20] and exploratory wells found the Yanhu Gas Field north of the lake the next year.