After slamming into Azeroth from the Great Dark Beyond, the Old Gods embedded themselves in the world's surface and sent their tentacles slithering towards the planet's defenseless core and its nascent world-soul. As they spread their corruptive influence across the land, two races arose from the organic matter that seeped from their blighted forms: the cunning n'raqi and the resilient aqir. The n'raqi, or "faceless ones", acted as taskmasters, employing the insectoid aqir to build massive citadels and temples around the massive bulks of their Old God masters. The greatest of these bastions was built around Y'Shaarj, the most powerful and wicked of the Old Gods, and soon these holdings would spread across the world, becoming known as the Black Empire. Massive sacrifices and living buildings filled with void energy were some of the distinguishing features of this shadowy domain.
The rise of the Black Empire did not go unnoticed by the Elemental Lords, who had previously been the only inhabitants of Azeroth. Seeing the Old Ones as a threat to their dominion, for the first time in Azeroth's history, the native spirits of the world united against a common enemy. Al'akir and Ragnaros cooperated to create blistering firestorms, reducing the Black Empire's citadels to ash. Therazane raised jagged rock walls to corral her enemies and shatter their temple cities. Neptulon crushed the n'raqi and aqir with the fury of the seas.
Ultimately, however, no matter how many n'raqi and aqir died, more and more would spawn from the Old Gods' putrid forms like larvae from a hive. The elementals could not stand against the endless swarms, and the Old Gods eventually succeeded in enslaving the Elemental Lords. Without the native spirits of the world to hinder the Black Empire's influence, the world spiraled into an abyss of death and suffering.