Su ‧ mer /ˈsuːməʳ/ BrE AmE
the southern part of ancient Mesopotamia (modern Iraq), where people called the Sumerians lived from about 3500 BC, in one of the world's earliest societies. One of the cities of Sumer was the city of Ur. The Sumerians developed a type of writing known as ↑ cuneiform , and are believed to have invented the wheel.