The Dragon Gate is located about 65km south of Hukou Waterfall, which is the open and flat Guanzhong Plain. The water of the Yellow River enters the river bed from Longmen, and the river property has changed greatly. The formation of Longmen is that Longmen Mountain in the east and Liangshan Mountain in the west each extend out of the ridge, close to each other, forming a narrow mouth only 1 meters wide, like a giant clamp, which binds the river and forms a swift current. Every flood season, because the water level in the gorge is high, the river valley suddenly widens and the water level suddenly drops after leaving the canyon, so there is an obvious water level difference in Longmen, so there is a saying that "Longmen falls into water three times". The story of "carp jumping at the dragon gate" passed down from generation to generation refers to the water falling here. The story tells that small carp are not afraid of dangers and obstacles, and they jump the gate on the road to Jackie Chan one after another. If they can jump over the past, they will become Jackie Chan. Only those indomitable little carp can finally become Jackie Chan. For thousands of years, this story has also inspired the descendants of the Chinese people to work hard and struggle endlessly. Ancient people felt incredible about the formation of Longmen Gorge, a natural wonder, and imagined it as a gorge cut by Dayu, so Longmen was also called "Yumenkou".

2. The story of Dayu's water control

It is said that during the reign of Emperor Yao, floods often occurred in the Yellow River basin. In order to stop flooding and protect agricultural production, Emperor Yao once called a meeting of tribal leaders to solicit experts in water control to quell water disasters. Gun was recommended to take charge of the work. After accepting the task, Gun used dikes to block the water, making a city of three blocks, that is, enclosing the residential area with simple dikes to block the flood, which failed for nine years, and finally he was exiled to Yushan and died. After Shun Di ascended the throne, Yu Zhi, the son of Gun, was appointed to control water. Yu summed up his father's experience in water control, and changed Gun's "blocking barrier" into "dredging and guiding stagnation", that is, using the natural trend of water flowing from high to low, consequent relief dredged the congested stream. The flood was introduced into dredged rivers, depressions or lakes, and then connected with the four seas, thus quelling the flood and enabling the people to move back from the highlands to Pingchuan to live and engage in agricultural production. Later, Yu became the first king of the Xia Dynasty and was called "Shen Yu".