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.
Prehistory
Human prehistory is the period between the use of the first stone tools 3.3 million years ago by hominins and the invention of writing systems. The earliest writing systems appeared 5,300 years ago, but it took thousands of years for writing to be widely adopted and it was not used in some human cultures until the 19th century or even until the present. The end of prehistory therefore came at very different dates in different places, and the term is less often used in discussing societies where prehistory ended relatively recently.