The Divine Expulsion

The Divine Expulsion is the event that ended the Second Era, expelling all Celestial and Daemonic beings from the material plane. After thousands of years of forced conflict between two forces, the Divenians, along with the Daemonic Tieflings, successfully using the magic granted to them against their immaterial masters to create a powerful barrier. Through untold cooperation and secret sorcery, they manage to harness places of power throughout the realm. The places are numerous and varied, yet all were taken on the High of Soulsworn 9144 BD, and at the Godgate a great spell was woven into the very fabric of the plane. Casting out the old gods, the Divine Gods, the spell made way for the way of the new gods, the Aodean Gods. The spell is devious in design, absorbing the divine power of beings who try and cross it, resulting in it being easier for lesser Celestials and Daemons to slip through.
However, over thousands of years and the waning of memory, the barrier has been chipped away at. Old gods have begun to seep back into the material plane, some even being embraced. The new ways of magic are being thrown into chaos, with several places of power being taken for self-serving purposes.