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.
Cradle of civilization
The earliest evidence of agriculture in the Andean region dates to around 4700 BC at Huaca Prieta and Paredones. The oldest evidence of canal irrigation in South America dates to 4700 to 2500 BC in the Zaña Valley of northern Peru. The earliest urban settlements of the Andes, as well as North and South America, are dated to 3500 BC at Huaricanga, in the Fortaleza area, and Sechin Bajo near the Sechin River.