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.
History of communication
The invention of the first writing systems is roughly contemporary with the beginning of the Bronze Age in the late Neolithic of the late 4000 BC. The first writing system is generally believed to have been invented in pre-historic Sumer and developed by the late 3000's BC into cuneiform. Egyptian hieroglyphs, and the undeciphered Proto-Elamite writing system and Indus Valley script also date to this era, though a few scholars have questioned the Indus Valley script's status as a writing system.