The term "Mesopotamian" refers to the ancient civilization that developed in the region between the Tigris and Euphrates rivers, primarily in present-day Iraq. This area is often called the "cradle of civilization" because it was one of the first places where complex societies emerged around 3500 BCE. The Mesopotamians are known for their advancements in writing, agriculture, and urban planning. Mesopotamian culture included various city-states, such as Sumer, Akkad, Babylon, and Assyria. They created one of the earliest writing systems, called cuneiform, and made significant contributions to mathematics, astronomy, and law, exemplified by the Code of Hammurabi. Their rich mythology and religious practices also influenced later cultures.