The Mesopotamian plains are located between the Tigris and Euphrates rivers, primarily in modern-day Iraq. This region is known for its fertile soil, which supported the growth of early civilizations. The abundance of water from the rivers allowed for agriculture, leading to the rise of cities and complex societies. These plains are often referred to as the "Cradle of Civilization" because they were home to some of the world's first urban centers, such as Sumer, Babylon, and Assyria. The rich resources and favorable climate contributed to advancements in writing, trade, and governance in ancient times.