It rises as several streams in a valley on the northern side of the Qilian Mountains or Nan Shan, on the Tibetan Plateau of extreme northern Qinghai province. In its upper the river flows generally NNW through deep, glacier-carved valleys and precipitous gorges into Gansu Province, and is known as the Changma. It comes out of the mountains in Guazhou County, and spreads onto a massive inland delta or alluvial fan. Now known as the Shule proper, the river turns due west into an agricultural valley, where most of its water is taken away for irrigation and industrial use. North of Dunhuang, the largest city in the river's basin, it disappears into the desert, after flowing some . The dry river channel stretches about further WSW to the seasonal Lop Nur basin, which comprises intermittent salt flats, playas and marshes.