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.
South Asia
The history of core South Asia begins with evidence of human activity of "Homo sapiens," as long as 75,000 years ago, or with earlier hominids including "Homo erectus" from about 500,000 years ago. The Indus Valley Civilization, which spread and flourished in the northwestern part of South Asia from c. 3300 to 1300 BCE in present-day Northern India, Pakistan and Afghanistan, was the first major civilization in South Asia. A sophisticated and technologically advanced urban culture developed in the Mature Harappan period, from 2600 to 1900 BCE.