The game takes place in a fantasy world, a planet called Ateria. The name Aion comes from the name of the God who ruled over this planet. He then created a set of servants to serve him, and named them the Balaur. The Balaur gradually gained power and rose in rebellion against their creator, Aion.

To oppose them, Aion created a dozen Empyrean Lords, and assigned them to protect the humans and other mortals. The Empyrean Lords created a barrier that acted as a deterrent against the Balaur, and all things inside this barrier was protected. 포커사이트

Slowly, humans living inside the barrier learned how to attain some of the powers of the Empyrean Lords and became known as the Daevas. They formed an army, and decided to battle the Balaur. The war continued for a long time, with no proper victory for both sides.

It was then decided to have peace talks with the Balaur in the Tower of Eternity, and the Balaur was invited. But the talks failed, and a violent fight erupted, and the Tower, along with the entire world, split into two, the Light and the Dark. Out of the twelve Empyrean Lords, only ten survived and split into two groups, the Shedim and Seraphim, presiding over the Dark and the Light parts respectively. The followers of the Seraphim are called the Elyos and followers of Shedim, Asmodians.