Imperial defeats come at the hands of enemies largely created by imperialism. YOU=PWNT. The Roman Empire was weakened by internal forces entirely related to imperialism. YOU=PWNT, AGAIN.
All Empires fall. They work HARD to destroy themselves, since constant and violent growth CANNOT be sustained.
Gawd, you Westerner FUCKS are goddamn DUMB. You live in one of the most evil empires to ever have existed, so you can't even see it. You're the best educated IMPERIAL MORONS to have ever existed. You can make quantum logic gates and isolate single electrons, but you can't see your own evil empire roll over Central America like a Nazi horde. BLIND!