The ancient civilization characterized by its city-states is Sumer, located in present-day southern Iraq. Sumer is recognized as one of the world’s earliest urban cultures, flourishing around 4500 BCE. Each city-state, such as Uruk, Ur, and Lagash, operated independently with its own government and deities, often engaging in both competition and cooperation with neighboring states. They are credited with numerous advancements, including the invention of writing (cuneiform), the wheel, and significant developments in mathematics and astronomy. Sumer's contributions laid the groundwork for successive civilizations in Mesopotamia and had a lasting influence on culture and governance.