According to legend, the underworld and the underworld are bounded by the blood-yellow Wangchuan River. There is a Naihe Bridge above the Wangchuan River. Meng Po receives guests who cross the bridge with soup every day, which can make them forget their past lives and re-enter reincarnation;
Heaven and earth were born out of chaos. After thousands of years, this river composed of countless creatures actually gave birth to a touch of aura of heaven and earth, and it was named Wangchuan.