The planet Cullum IV was the homeworld of the Cullum. It is located on the Cullum Trade Corridor in the Valcarian Empire's Outlying Territories region. It is an incredibly harsh world with heavy gravity, a poisonous atmosphere, a constant rain of meteors, and huge plains of lava and exposed radioactive metals.
The merchant-oriented Cullum created domed cities on their world to house offworlders. Cullum IV was hit hard by the Valcarian Empire, for its manufacturing centers were among the first to be commandeered during the latest resurgence of Expansionism.
The otherwise docile species tried to fight back, but the endless slaughter which followed convinced them to be pragmatic about the situation. It was not practical to die fighting a superior enemy, the Cullum decided. When the smoke cleared and the dead were buried, they submitted completely to the Empire's will. Fortunately, they ceased resistance while their infrastructure was still intact.