Mesopotamia: Between Two Rivers

The Tigris and Euphrates created the Fertile Crescent in modern-day Iraq, where the Sumerians invented writing, the wheel, mathematics, and organized law around 3500 BCE. Unlike the Nile, these rivers flooded unpredictably, forcing people to build canals and dikes to tame the water and protect their fields.

The need to manage water drove the creation of bureaucracy and law. Hammurabi's Code — one of the oldest written legal systems — includes rules about irrigation rights and penalties for neglecting canal maintenance.