<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 lived in cities along the Tigris and Euphrates Rivers. The Sumerians created the world’s first writing system and developed the world’s first cities. The Sumerians invented agriculture and the wheel, and were the first to domesticate animals and grow crops.