Historians generally divide Sumerian history into three…

Historians generally divide Sumerian history into three stages.

The most important political development in the first stage, which extends roughly from 3360 BCE to 2400 BCE, is the emergence of kings who, unlike the first priestly rulers, exercised distinct political rather than religious authority.

Another important feature of this period is the emergence of warring Sumerian city-states, which fight for control of the river valleys in lower Mesopotamia.