In ancient times, the demon king Chiyou violated the agreement of the six realms and invaded the human realm with his troops, burning, killing, looting and committing all kinds of evil. The human world couldn't bear the disturbance, so they joined forces with the fairy world to fight against each other, and the three parties launched a fierce battle in Zhuolu. Chi You's excessive arrogance led to the defeat of the demon army, and he was beheaded by the captives. The demon world, which had lost its leader, retreated to the wilderness mountains under the leadership of the new demon king Chi Yan. After the war, the Immortal Realm was regrouping and recuperating, and its defenses were also very lax. The Demonic Realm took this opportunity to steal the ancient artifact Shan Hai Jing stored in the Yao Chi for purification. The demon world broke the seal of the Classic of Mountains and Seas and released countless evil spirits and miasmas, trying to use them to unify the six realms.