Human: Who were the first people to settle in the area of the Tigris and Euphrates? Assistant: 
The area was inhabited by the Sumerians, who were the first known civilization in the area. The Sumerians were one of the earliest known civilizations in the world. They were responsible for developing writing and city-states, and they developed the first known system of laws and government. They developed a number of innovations, including the use of the wheel, the potter's wheel, and the plow.