Early civilizations emerged around 3500 BCE in regions like the Mesopotamia, Egypt, and the Indus Valley. These societies developed complex social structures, writing systems, and advanced agricultural practices. They built cities, established trade networks, and created laws to govern their communities. Key features of early civilizations included the rise of city-states, the invention of writing for record-keeping, and advancements in technology such as the wheel and irrigation systems. Notable early civilizations also included the Chinese dynasties and the Mesoamerican cultures, which contributed significantly to human history and cultural development.