How did political centralization develop in Tigris and Euphrates rivers?

Answer 1

Political centralization in the Tigris and Euphrates river valleys developed through the establishment of city-states, such as Sumerian cities, which emerged around 3000 BCE. These city-states organized agricultural production, trade, and labor, facilitating the accumulation of resources and power. The formation of bureaucracies and the use of writing for record-keeping further enabled centralized governance. Additionally, the need for irrigation management and defense against external threats spurred cooperation and centralized authority among the city-states.