The culture known for the creation of the first complex cities and governments is the Sumerian civilization. Flourishing in Mesopotamia, Sumerians established city-states such as Ur, Uruk, and Lagash around 3500 to 3000 BCE. They developed organized governments led by priest-kings and established social hierarchies alongside complex economic systems that included trade, agriculture, and writing. Their innovations in writing (cuneiform), mathematics, and temple architecture significantly influenced subsequent civilizations in the region and beyond. Sumerians' advancements laid foundational elements of urban life, governance, and culture that shaped human history and set benchmarks for later societies in the ancient world.