Yue longmen, a carp, originated from the story that many carp were washed out of Dayu by water control during the Dayu period. Carps cross the dragon gate, and dragons can soar. Later, in the imperial examination era, people who took the exam and won the fame of Jinshi were also called "boarding the Dragon Gate". Because of its auspicious meaning, it is also one of the traditional auspicious patterns in China.

According to legend, a long time ago, the Yellow River flooded. Shun used Da Yu, the son of Gun, to inherit his father's business and control floods. Yu's method of controlling water is dredging. The jade emperor ordered his youngest daughter to descend to earth, turned her into a native girl, and married Dayu to help him control the water. Dayu dredged the flood of the Yellow River to the northwest of Hejin, Shanxi Province, and the northeast of Hancheng, Shaanxi Province, across the banks of the Yellow River, shaped like a cliff mouth of a mountain gate, and finally diverted the flood. This mouth 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. The carp could not go upstream and returned to their hometown, so they protested to the Dayu couple. Tushan said with a smile, "I'll invite the Jade Emperor to play. Those who can leap over the gap will stand in Ma Hualong, soaring to the sky and having broken foreheads and cheeks. They can only blame themselves for being ordinary, so stop it. " . "From then on, every spring season, countless golden carp followed the Yellow River upstream, gathered in Yumen, struggling 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 story of "yue longmen the Carp" is often expressed by the leading octopus. This wall shows that in the rolling river waves, carp spit under Yumen, leap over Yumen and become a dragon, spreading its wings and flying into the sky.