The train runs southward from the northern gateway of Hoh Xil Nature Reserve to the southern gateway, where lies the Tuotuo River, which is one of the three headwaters of the Yangtze River. Viewed from the right-hand side windows of the train, the water sources to take shape of the Tuotuo River are merely tricklets without momentum. Yet they amalgamate and accumulate their force arduously all the way from such remote areas to form the Yangtze River. It is the mighty Yangtze River that mothers a nation of five-thousand-year’s civilization. After crossing the Tuotuo River, the train is heading to Tonggula Mountain Pass.