S E C T I O N 3 City-States of Ancient Sumer. Sumer, the oldest civilization of the Middle East. Fertile Crescent. . Sumer. Sumer developed in Mesopotamia, a rich, fertile land between the Tigris and Euphrates rivers.. . Sumer created Irrigation and Flood Control by building dikes and canals . . Sumer was made up of many city-states.