The first civilization to develop urban centers in Mesopotamia was the Sumerians. They established city-states around 3500 BCE, featuring complex societal structures, monumental architecture, and advancements in writing and governance. Cities such as Uruk, Ur, and Eridu exemplify Sumerian urbanization, where trade, agriculture, and administration flourished. The Sumerians also pioneered technologies such as the wheel and cuneiform writing, which greatly influenced subsequent civilizations in the region.