Xuanwu was the earthy protector against the flood, a mythological beast of the ancient times. Legend has it that, in the war fought between Gods and Demons in the distant past, a branch of the Divine Tree was snapped off; it landed next to a vast river and stood firmly on the river bank. The lands around the river was fertile and many people settled there. The great branch grew no leaves but nor did it rot. Every time the river overflowed, people would tie themselves to the branch with numerous tree vines. The wooden stake was therefore worshiped by the people and was given the title of “Xuanwu”. When demons attacked the people, the great branch transformed into a giant turtle while the tree vines into a green snake. The giant tortoise fended off the attacking demons and drove them away. After that, the giant beast dived into the water and the river never flooded since then.
It was the time when the war between Gods and Demons erupted once again. The young Hermit of the Vague Territory was drowning in the river. His teacher dived into the water to rescue him, but saw a small turtle with a snake tail pushing the child up onto the river bank. When it was about to dive back after returning the child to the ascetics, it was captured by the hermit’s mentor. The mentor of the hermit had always kept the little tortoise by his side until he participated in the war. He then left the beast to the his apprentice. The young hermit and Xuanwu refined their power and skills together. The hermit soon discovered that Xuanwu had been conducting its power to the earth, leaving itself in a weakened state. Therefore, the hermit shared the power that he acquired with the tortoise, hoping that the beast could regain its power and fight the demons. The two protected the weak on the battlefield, punished only the evil-doers and defended people with their rock-like bodies. The other ascetics called them “the Sage of the North”, one of the “Four Sages”.