The Yangtze River - the longest river in China. Because its source is called "Zhiqu" in Tibetan, which means "cow" and "qu" is the name of a river, it is called "the river of cows". Zhiduo County, Yushu Tibetan Autonomous Prefecture, Qinghai Province, is the source of the Yangtze River and is known as the "first county of the Yangtze River".