Sumeria's government was comprised of city-states that were ruled by a priesthood. The city states were organized around a temple.
Sumeria, which was located around the Euphrates and Tigris Rivers around 4000 B.C., featured distinct social and governmental structures. As it was organized around a temple, the majority of its residents were thought to be servants and slaves of the god of that temple.
After some time, the city-states of Sumeria formed alliances and as a result, wars of defense formed as well. Because of this, the power of the priesthood fell off a bit because warriors were able to bring forth the dominance of the kings in the region.