The birthplace of the earliest known civilization lies between the Tigris and Euphrates rivers, at the southernmost tip of Mesopotamia, and later became Babylonia (now southern Iraq, from around Baghdad to the Persian Gulf). 4500 BC? During the first 4,000 years, a group of non-Sem people (now known as primitive Euphrates or [Ubaidian] people) first settled here. After the Obeid people moved to Mesopotamia, different Sumerians infiltrated their territory, merged their own culture with Obeid culture, and created a highly pre-Soviet-American civilization.