 In the late 4th millennium BC, Sumer was divided into many independent city-states, which were divided by canals and boundary stones.Each was centered on a temple dedicated to the particular patron god or goddess of the city and ruled over by a priestly governor (ensi) or by a king (lugal) who was intimately tied to the city's religious rites.The five "first" cities, said to have exercised pre-dynastic kingship "before the flood"