o established some type of organized government bureaucracy to meet the administrative demands of the population, and a new social structure developed based one economic power.
Sometime in the fourth millennium B.C. in southwest Asia there appeared in quick succession a group of culture foci, among them those which would eventually give rise to the self-contained and characteristic civilizations which have been identified by the names of the river valleys that harbored them, those of the Indus Valley, the Euphrates Valley, and the Nile Valley. Mesopotamia was the area between the Tigris and Euphrates rivers in what we now call the Near East. There is little rain in this region, but the soil of the plain had been enhanced over the centuries by layers of silt deposited by the two rivers, deposited as the two rivers overflow their banks in late spring each year. Such flooding depends on the melting of snows in the upland mountains and so is irregular. Farming was possible only through irrigation and drainage by the people who settled there, and this required a complex system to control the flow of rivers and produce the crops. Mesopotamian civilization involved different peoples, but it began with the Sumerians in the area between the two rivers.
The earliest periods, corresponding to the Longshan and earlier eras in China, were the Eridu period from about 5500 to 4500 B.C., the Al 'Ubaid period to 3500 B.C., and the Uruk period after 3000 B.C. As noted, the civilization in the Euphrates region developed earlier than that in China, and by the fourth millennium settlements such as Eridu, Uruk, and Ur had grown into townships and then into populous cities marked by monumental temples. By 3000 B.C., Sumeria was divided into city states with powerful royal courts and priesthoods, and these rulers employed a variety of skilled craftsmen, importing metals and precious stones from the hill country. They also invented writing ...