22,000 BCE
The Anti-oan flaw in reality corrupts the Manhunters and they attack Oa. The Controllers insist in rebuilding them, and are eventually cast out of Oa by the Guardians, who construct the Central Oan Power Battery and begin building the Green Lantern Corps.
The fall of the Manhunters leaves a power vacuum that leads to the rise of the Arakacian Terror Fleet, and begin breeding their biological death engines, the Stygomorph.