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
The Bronze Age is the earliest period in which some civilizations have reached the end of prehistory, by introducing written records. The Bronze Age or parts thereof are thus considered to be part of prehistory only for the regions and civilizations who adopted or developed a system of keeping written records during later periods. The invention of writing coincides in some areas with the early beginnings of the Bronze Age. Soon after the appearance of writing, people started creating texts including written accounts of events and records of administrative matters.