Irrigation and the First Surplus

In the flat, rainless south of Mesopotamia — the land between the Tigris and Euphrates rivers, in modern southern Iraq — farmers dug canals to spread the rivers' water across their fields. The payoff: enough grain to feed people who never farmed at all — priests, soldiers, scribes, chiefs. That surplus is the opening turn of a wheel that runs through this whole story: stored wealth lets a few accumulate far more than the rest, building up until some shock — plague, war, collapse — levels it flat again.