A massive meteor strike has devastated Earth. Human civilization comes to an end in the ensuing cataclysms and humanity regresses into tribes of Stone Age dwellers. A primordial rainforest covers the land and the continental landmass has shifted into the shape of a fire-breathing dinosaur skull. The planet is now primitively referred to as "Urth" by the survivors of the cataclysms.

Seven fearsome creatures emerge from their slumber deep within the Urth's crust, and become worshiped as gods by the humans, who form segregated clans beneath the ones they follow. The beasts themselves are divided between those who wish to keep peace on Urth, and those who attempt to plunge the world into further chaos for their own benefit.