There are different opinions about the legend of the upstream river. To the east of Riyueshan Mountain, the Han people have said for thousands of years that in order to communicate the relationship between the Tibetan and Han nationalities and promote cultural exchanges, Tang Wang Li Shimin married the young and beautiful Wencheng princess to Tubo Songzan Ganbu. On her way to Tibet, Princess Wencheng did not see Chang'an when she arrived at Riyueshan Mountain. She looked to the West desolately, missed her hometown, missed her parents, and was grieved. She moved westward with tears, and the princess's tears converged into this upside-down river. To the west of Riyueshan Mountain, another myth circulated among Tibetans: the Dragon King sent his four sons and daughters to build four rivers, north and south, East and west. When the youngest daughter built the West Sea, 108 rivers were needed. She found 107 rivers, and the last one could not be found. The wise and cunning dragon lady brought a river from the Sun Moon Mountains upside down. This river is the upside down river. The third way of saying is that this river is the reverse of the Dragon king. There is no need to examine which legend is more authoritative, which myth is closer to the orthodox, and each legend adds a mystery to it. And finally one day, when you come to it with the passion of exploration and search, you can hear a sigh, a whisper, a gentle whisper, and it seems that there are ten thousand kinds of tender intestines. Then you will realize that this is a woman's river.