The Cultural Revolutions from the beginning to the USA today

If we broadly analyze only a few of the ¿Cultural Revolutions¿ that the human history has witnessed, we shall notice that they are bizarre events of great amplitude, throughout which important states such as the USSR, China or the USA have mainly hurt themselves, by destroying world heritage values. It comes to confirm once more the theory that the great empires, apparently almighty and which cannot be conquered from outside, would self-demolish and crumble from the inside.