 The Tuotuo River () is the official headstream of the Yangtze, and flows from the glaciers of the Gar Kangri and the Geladandong Massifs in the Tanggula Mountains of southwestern Qinghai to the confluence with the Dangqu River to form the Tongtian River.In Mongolian, this section of the river known as the "Ulaan Mörön" or the "Red River.