What is the importance of a mesopatania city state?

A city-state functioned much as an independent country does today. Sumerian city-states included Uruk, Kish, Lagash, Umma, and Ur. In the center of all Sumerian city-states was the walled temple with a ziggurat in the middle. There the priests and rulers appealed to the gods for the well-being of the city-state. (McDougal Littell, World History: Patterns of Interactions, p.31)