Third Dynasty of Ur
The Third Dynasty of Ur is dated to ca. 2047–1940 BC short chronology. Ur-Nammu of Ur defeated Utu-hegal of Uruk and founded the Third Dynasty of Ur. Although the Sumerian language ("Emegir") was again made official, Sumerian identity was already in decline, as the population became continually more and more Semiticised.
After the Ur III dynasty was destroyed by the Elamites in 2004 BC, a fierce rivalry developed between the city-states of Larsa, more under Elamite than Sumerian influence, and Isin, that was more Amorite (as the Western Semitic nomads were called). Archaeologically, the fall of the Ur III dynasty corresponds to the beginning of the Middle Bronze Age. The Semites ended up prevailing in Mesopotamia by the time of Hammurabi of Babylon, who founded the Babylonian Empire, and the language and name of Sumer gradually passed into the realm of antiquarian scholars. Nevertheless, Sumerian influence on Babylonia, and all subsequent cultures in the region, was undeniably great.
During the third millennium BC, there developed a very intimate cultural symbiosis between the Sumerians and the Akkadians, which included widespread bilingualism. The influence of Sumerian on Akkadian (and vice versa) is evident in all areas, from lexical borrowing on a massive scale, to syntactic, morphological, and phonological convergence. This has prompted scholars to refer to Sumerian and Akkadian in the third millennium as a sprachbund.
Akkadian gradually replaced Sumerian as the spoken language of Mesopotamia somewhere around the turn of the third and the second millennium BC (the exact dating being a matter of debate), but Sumerian continued to be used as a sacred, ceremonial, literary and scientific language in Mesopotamia until the first century AD.
Read more about this topic: History Of Sumer