The shape of Mesopotamia can be described as roughly rectangular, with the long sides running northwest to southeast and the shorter sides running northeast to southwest. The Tigris and Euphrates rivers flow through the region from northwest to southeast, dividing it into two main parts: Upper Mesopotamia and Lower Mesopotamia.
Upper Mesopotamia, also known as the Jazira, lies to the north and west of the Tigris and Euphrates rivers. It is a region of rolling hills and plains, with some areas of desert and mountains. Lower Mesopotamia, also known as the Alluvial Plain, lies to the south and east of the Tigris and Euphrates rivers. It is a flat, fertile plain that is home to some of the world's oldest civilizations, including the Sumerian, Babylonian, and Assyrian civilizations.