Named in honor of one of the oldest known civilizations, located in the southernmost part of Mesopotamia between the Tigris and Euphrates rivers. It was first settled between 4500 to 4000 B.C., probably shortly after JD 0, by Ubaidans. The Sumerians themselves arrived around 3300 B.C. and lost their separate identity around 1900 B.C. when conquered by the Amorites. The Sumerians contributed many technological and cultural innovations, among them the first wheeled vehicles and potter’s wheels, the first system of writing, the first written codes of law, and the first city-state. (M 21128) _ _.