The Great War
A great war was waged between the old gods and the denizens of the world. A great many people dies. Some where wiped out. Some were changed and affected. The world and its land ravaged. But eventually the denizens won and slaughtered the old gods. Some went into hiding but few survived compared to how many there once was. Now littered with their corpses, their lingering memories giving off great magical essences littering and polluting the world.