Civilizations normally go through three stages; Barbaric, Vigorous and Decadent.
It’s easy to find examples of barbaric and decadent civilizations. We can find all the barbaric civilizations to suit an entire faculty’s worth of anthropologists in the Middle East. And then back home we can see the decadent civilization that employs their kind to bemoan the West.
Vigorous is what America used to be when it was moving west, producing at record rates and becoming a world power. Decadent is what it is becoming.
The barbaric civilization is the simplest of all. It runs on kinship. Pre-rational, it operates on explosions of emotion. It has no concept of enduring facts or objective reasoning. It holds life cheaply and kills casually. It loathes outsiders and has no universal laws. It is ruled by hierarchies which gain their position through brutality and trickery.