It is believed that Io had arisen from the Elemental Chaos and had created dragonkind as the first mortal creatures, the dragons being composed of the primal elements themselves. After creation, an event known as The Dawn War would take place where the primordials and deities would engage in a great war. During the war, the primordial Zehir, would kill Io and several of his descendants to claim his own Divinity.
According to legend, the two halves of Io then reformed into the two Dragon gods, Bahamut and Tiamat.