Why did civilizations develop near rivers?

The correlation between major rivers and early civilizations is so strong that historians have a name for it: "river valley civilizations." The Tigris and Euphrates supported Mesopotamia, the Nile sustained Egypt, the Indus nourished the Indus Valley Civilization, and the Yellow River gave rise to Chinese civilization. This was no coincidence — rivers provided everything complex societies needed to develop.

First and most importantly, rivers provided water for irrigation. In the semi-arid landscapes of Mesopotamia and Egypt, rainfall alone was insufficient for agriculture. Irrigation channels allowed farmers to direct river water to their fields, transforming barren land into some of the most productive farmland on Earth. The Nile's annual flood deposited fresh, fertile silt across the floodplain, naturally renewing the soil.

Rivers also served as transportation highways. Moving goods overland was slow and expensive; boats could carry large quantities of grain, building materials, and trade goods quickly and cheaply. This facilitated trade, communication, and political unification — Egypt's early unity, for example, was partly enabled by the Nile's role as a single north-south highway.

Finally, the organizational demands of water management may have helped drive political complexity. Building and maintaining irrigation systems required coordination, planning, and authority. This "hydraulic hypothesis," while now considered too simplistic as a single explanation, captures an important truth: managing shared water resources created incentives for the centralized governance that characterizes civilizations.