Empire man. Zealot

Have been many “wild” empires in history when conditional barbarians seized large territories with more developed peoples. But the savage empires quickly crumbled. What is the reason? The simplification of the world is the main reason for the death of an empire. Simple organisms die faster. More the internal imperial bacilli lead to death. And only the Zealots (super people), changing the vector from simplification to a new one, could do something.