According to legend, a long time ago, the Yellow River flooded. Dayu, the son of Shunkai stick, inherited his father's business and used dredging to control water, which eventually led to flood diversion. This valley is called Yumen.

Carp living in the Yellow River was rushed out of Yumen and suddenly fell from a waterfall more than ten feet deep. So the carp could not go upstream and returned to their hometown, so they protested to the Dayu couple. Dayu's wife said: those who can leap into the gap will immediately become dragons and soar into the sky. Go home if you can't jump, and don't make trouble here.

From then on, in the late spring, countless golden carp went upstream along the Yellow River, gathered in Yumen and struggled to jump. Occasionally, the one who jumps over becomes a black dragon and takes off for nine days. The Yumenguan Gate where the dragon looks up is called "Longmen", which means "one yue longmen is worth a hundred times".

The reason why expansion data sneaked into Longmen

"Carp", also known as sturgeon, is a migratory fish with a body length of about two meters and a maximum length of more than five meters. Chinese sturgeon, northeast sturgeon, Yangtze sturgeon and other rare animals in China are all this kind of fish.

Sturgeon didn't come to Longmen to "leap the dragon", but to breed. According to "Study on Biology and Artificial Propagation of Acipenser Changjiang" written by Sichuan Yangtze River Fishery Resources Investigation Team, Acipenser Changjiang mostly lays eggs in the upper reaches of the river, with low water temperature, high velocity, complex flow pattern, wide and narrow river channel and sandy bottom. Longmen area, at the junction of Shan State and Shan State, is an ideal place for sturgeons to gather and lay eggs because of the above landform characteristics.

References:

Baidu Encyclopedia-Long yue longmen