Modern name for the country in southern Babylonia (south of Nippur) that the Sumerians called kengi. The Akkadian inscriptions speak of Sumer (sumerum) and (the northern) Akkad as constituent of the “country.” Although Sumer was never a coherent political unit, it was linked by cultural and economic practices and norms and the acceptance of urbanism. Already in the fourth millennium B.C. (Uruk period), such links can be surmised from the way the city seals appear in administrative texts and lists. In the Early Dynastic period, there was great rivalry between individual cities and competition over water rights that led to armed clashes. On the other hand, there is also evidence of collective action, which could mobilize large numbers of people in common tasks.
Historical Dictionary of Mesopotamia. EdwART. 2012.