The oldest known civilization is generally recognized as the Sumerians, who emerged in Mesopotamia around 3500 BCE. Located in what is now southern Iraq, the Sumerians developed one of the first complex societies, marked by innovations such as writing (cuneiform), mathematics, and advanced architectural techniques. They established city-states like Ur and Uruk, which were characterized by monumental temples and ziggurats. Sumerian culture laid the foundation for subsequent civilizations in the region, influencing legal systems, literature, and trade, thus playing a significant role in human history.