<human>:  Who were the first people to settle in the area of the Tigris and Euphrates?
<bot>: The area was inhabited by the Sumerians, who were the first known civilization in the area. The Sumerians were a group of people who lived in southern Mesopotamia (the land between the Tigris and Euphrates rivers). They were the first people to settle the area, and they created the first known writing system in the world.