The Tigris and Euphrates Rivers are the most important physical features of the region known as Mesopotamia. It means “between the rivers” in Greek. This region is part of a larger area called the Fertile Crescent, a large arc of rich, or fertile, farmland. It extends from the Persian Gulf to the Mediterranean Sea. The Tigris and Euphrates Rivers flow down this region from the hills in the north to the low-lying plains in the south.