The Sumerians, as they were called later by their Semitic conquerors, were people of Kengir, now southern Iraq, in Mesopotamia. Their origins are somewhat of a mystery. One theory holds that these non-Semitic people migrated to Mesopotamia from Central Asia in the fourth millennium B.C.E. and mixed with other non-Semitic people, the Ubaids, who had established protocities along the marshlands in the area and had been there at least since the fifth millennium B.C.E. These settlements would evolve into the famous Sumerian cities of Ur, Eridu, Unug (Uruk) and Nippur. These were city-states with a linguistic, legal, religious, political, and architectural basis that would influence the area—including its mythology—long after the Sumerians were conquered by the Semitic Akkadians led by Sargon I late in the third millennium B.C.E. and, after a resurgence, by the Semitic Babylonians in the second millennium B.C.E.