There are five dragon kings in Taoism, and the Black Dragon God is one of them. Five directions correspond to five colors, which originated from China's concept of five elements. The black dragon is the dragon god in charge of the north and the fifth owner of the dragon.
Taoism is a native religion in China, the only religion that originated in China and was founded by China people, and it is one of the three spiritual pillars of the ancient ruling class. "Solemnly declare: The answer is for reference only, please don't be blindly superstitious."