The ancient civilization that flourished in the region of Mesopotamia was the Sumerians. Often regarded as one of the world's first civilizations, they settled in the southern part of Mesopotamia (modern-day Iraq) around 4500 BC. The Sumerians were known for their advancements in various fields, including writing (cuneiform), mathematics, and astronomy. They established city-states such as Ur, Uruk, and Eridu, and built complex societies governed by a mix of religious and political authorities. They are also credited with innovations like the wheel and the concept of time, significantly influencing subsequent civilizations in Mesopotamia and beyond, such as the Akkadians and Babylonians.