The Dawn War
The Dawn War was a conflict on an unimaginable scale, fought between the gods of the Astral Sea and the primordials of the Elemental Chaos. The war started after a being known as The Elder Elemental Eye attempted to gain control of the Pure Shard, located at the bottom of the Abyss. The Elder Elemental Eye rallied many of the primordials to its banner, and when the plans became known to the gods, they intervened. The resulting war between god and primordial lasted for over a millennium, and none of the planes were safe from the conflict. The material realm became a battleground between these titanic forces, and the mortals residing there became embroiled in both sides of the war.
The end of the war came about after three events. First, the primordials known as the archomentals switched sides after seeing the true aim of the Elder Elemental Eye. Secondly, the primal spirits of the material realm, growing tired of both the gods and primordials, rose up and banished both parties from appearing directly upon the material plane. Lastly, the combined might of the gods and their new found allies was too much for the Elder Elemental Eye. His armies were scattered, and the being itself was sealed away in a prison deep within the Far Realm.