History of the world
Whether in prehistoric or historic times, people always needed to be near reliable sources of potable water. Settlements developed on river banks as early as 3000 BCE in Mesopotamia, on the banks of Egypt's Nile River, in the Indus River valley, and along China's rivers. As farming developed, grain agriculture became more sophisticated and prompted a division of labour to store food between growing seasons. Labour divisions led to the rise of a leisured upper class and the development of cities, which provided the foundation for civilization. The growing complexity of human societies necessitated systems of accounting and writing.
Valdivia culture
The Valdivia culture is one of the oldest settled cultures recorded in the Americas. It emerged from the earlier Las Vegas culture and thrived on the Santa Elena peninsula near the modern-day town of Valdivia, Ecuador between 3500 BC and 1500 BC.