The main course of the river starts in the Qilian mountains at an elevation of 3650 m asl. The loamy sediment load gives the waters a dark colour which, during time, has contributed to the river being described as Hei (黑), that is Black. The orography in this part is obviously quite steep, with elevation peaks up to 5544 m asl and vegetation mainly made up of wild shrubs. Most of the precipitation fallen annually over the basin is concentrated in this area, creating two main river courses that join just north of the hydrometric station of Yingluo.