What is the earliest known civilization?
History of the world
3000 BCE in Mesopotamia
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,[3] on the banks of Egypt's Nile River,[4][5] in the Indus River valley,[6] and along China's rivers.[7][8]  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.