For a long time Diablo, Mephisto and Baal were battling against the hordes of rebel [[demon]]s in the Burning Hells, and killed a great number of them, but were eventually defeated and banished to walk the mortal world of [[Sanctuary]] as shades. After the exile, the rule of the Burning Hells fell in the hands of Azmodan and Belial, who were reluctant to share the supreme rule between the two of them. This resulted in a number of demonic civil wars for the throne, which have lasted to this day.