Sumer may very well be the first civilization in the world (although long term settlements at Jericho and Çatal Hüyük predate Sumer and examples of writing from Egypt and the Harappa, Indus valley sites may predate those from Sumer). From its beginnings as a collection of farming villages around 5000 BCE, through its conquest by Sargon of Agade around 2370 BCE and its final collapse under the Amorites around 2000 BCE, the Sumerians developed a religion and a society which influenced both their neighbors and their conquerors. Sumerian cuneiform, the earliest written language, was borrowed by the Babylonians, who also took many of their religious beliefs. In fact, traces and parallels of Sumerian myth can be found in Genesis.
Sumer was a collection of city states around the Lower Tigris and Euphrates rivers in what is now southern Iraq. Each of these cities had individual rulers, although as early as the mid-fourth millennium BCE the leader of the dominant city could have been considered the king of the region. The history of Sumer tends to be divided into five periods. They are the Uruk period, which saw the dominance of the city of that same name, the Jemdat Nasr period, the Early Dynastic periods, the Agade period, and the Ur III period - the entire span lasting from 3800 BCE to around 2000 BCE. In addition, there is evidence of the Sumerians in the area both prior to the Uruk period and after the Ur III Dynastic period, but relatively little is known about the former age and the latter time period is most heavily dominated by the Babylonians.
The Uruk period, stretched from 3800 BCE to 3200 BCE. It is to this era that the Sumerian King Lists ascribe the reigns of Dumuzi the shepherd, and the other antediluvian kings. After his reign Dumuzi was worshipped as the god of the spring grains. This time saw an enormous growth in urbanization such that Uruk probably had a population around 45,000 at the period's end. It was easily the largest city in the area, although the older cities of Eridu to the south and Kish to the north may have rivaled it. Irrigation improvements as well as a supply of raw materials for craftsmen provided an impetus for this growth. In fact, the city of An and Inanna also seems to have been at the heart of a trade network which stretched from what is now southern Turkey to what is now eastern Iran. In addition people were drawn to the city by the great temples there.
The Eanna of Uruk, a collection of temples dedicated to Inanna, was constructed at this time and bore many mosaics and frescoes. These buildings served civic as well as religious purposes, which was fitting as the en, or high priest, served as both the spiritual and temporal leader. The temples were places where craftsmen would practice their trades and where surplus food would be stored and distributed.
The Jemdat Nasr period lasted from 3200 BCE to 2900 BCE. It was not particularly remarkable and most adequately described as an extension and slowing down of the Uruk period. This is the period during which the great flood is supposed to have taken place. The Sumerians' account of the flood may have been based on a flooding of the Tigris, Euphrates, or both rivers onto their already marshy country.
The Early Dynastic period ran from 2900 BCE to 2370 BCE and it is this period for which we begin to have more reliable written accounts although some of the great kings of this era later evolved mythic tales about them and were deified. Kingship moved about 100 miles upriver and about 50 miles south of modern Bahgdad to the city of Kish. One of the earlier kings in Kish was Etana who "stabilized all the lands" securing the First Dynasty of Kish and establishing rule over Sumer and some of its neighbors. Etana was later believed by the Babylonians to have rode to heaven on the back of a giant Eagle so that he could receive the "plant of birth" from Ishtar (their version of Inanna) and thereby produce an heir.
Meanwhile, in the south, the Dynasty of Erech was founded by Meskiaggasher, who, along with his successors, was termed the "son of Utu", the sun-god. Following three other kings, including another Dumuzi, the famous Gilgamesh took the throne of Erech around 2600 BCE and became in volved in a power struggle for the region with the Kish Dynasts and with Mesannepadda, the founder of the Dynasty of Ur. While Gilgamesh became a demi-god, remembered in epic tales, it was Mesannepadda who was eventually victorious in this three-way power struggle, taking the by then traditional title of "King of Kish".
Although the dynasties of Kish and Erech fell by the wayside, Ur could not retain a strong hold over all of Sumer. The entire region was weakened by the struggle and individual city-states continued more or less independent rule. The rulers of Lagash declared themselves "Kings of Kish" around 2450 BCE, but failed to seriously control the region, facing several military challenges by the nearby Umma. Lugalzagesi, ensi or priest-king of Umma from around BCE, razed Lagash, and conquered Sumer, declaring himself "king of Erech and the Land". Unfortunately for him, all of this strife made Sumer ripe for conquest by an outsider and Sargon of Agade seized that opportunity.
Sargon united both Sumer and the northern region of Akkad - from which Babylon would arise about four hundred years later - not very far from Kish. Evidence is sketchy, but he may have extended his realm from the Medeterranian Sea to the Indus River. This unity would survive its founder by less than 40 years. He built the city of Agade and established an enormous court there and he had a new temple erected in Nippur. Trade from across his new empire and beyond swelled the city, making it the center of world culture for a brief time.
After Sargon's death, however, the empire was fraught with rebellion. Naram-Sin, Sargon's grandson and third successor, quelled the rebellions through a series of military successes, extending his realm. He declared himself 'King of the Four corners of the World' and had himself deified. His divine powers must have failed him as the Guti, a mountain people, razed Agade and deposed Naram-Sin, ending that dynasty.
After a few decades, the Guti presence became intolerable for the Sumerian leaders. Utuhegal of Uruk/Erech rallied a coalition army and ousted them. One of his lieutenants, Ur-Nammu, usurped his rule and established the third Ur dynasty around 2112 BCE. He consolidated his control by defeating a rival dynast in Lagash and soon gained control of all of the Sumerian city-states. He established the earliest known recorded law-codes and had constructed the great ziggurat of Ur, a kind of step-pyramid which stood over 60' tall and more than 200' wide. For the next century the Sumerians were extremely prosperous, but their society collapsed around 2000 BCE under the invading Amorites. A couple of city-states maintained their independence for a short while, but soon they and the rest of the Sumerians were absorbed into the rising empire of the Babylonians. (Crawford pp. 1-28; Kramer 1963 pp. 40-72)
Seated along the Euphrates River, Sumer had a thriving agriculture and trade industry. Herds of sheep and goats and farms of grains and vegetables were held both by the temples and private citizens. Ships plied up and down the river and throughout the Persian gulf, carrying pottery and various processed goods and bringing back fruits and various raw materials from across the region, including cedars from the Levant.
Sumer was one of the first literate civilizations leaving many records of business transactions, and lessons from schools. They had strong armies, which with their chariots and phalanxes held sway over their less civilized neighbors (Kramer 1963, p. 74). Perhaps the most lasting cultural remnants of the Sumerians though, can be found in their reli