The Elemental Planes

The Elemental planes were created thousands of years before present time. During the time of the Rampage of the Behemoths, gigantic elemental monsters known as the Behemoths were attacking Baltharos. The gods, at the time, wanted to preserve this newfound pocket of creation so they went to war with the Behemoths. The war was not easily won, in fact it was pretty much a tie. The Behemoths with their raw elemental strength caused the divine powers of the gods to create special weapons known as the Regalia.   Equiped with these new artifacts the gods banished the Behemoths off the face of the material plane. They were then imprisoned off-world in their own plane of existance. Their literal bodies became the elemental planes we know today.