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.
Ancient history
The 10th millennium BC is the earliest given date for the invention of agriculture and the beginning of the ancient era. Göbekli Tepe was erected by hunter-gatherers in the 10th millennium BC (c. 11,500 years ago), before the advent of sedentism. Together with Nevalı Çori, it has revolutionized understanding of the Eurasian Neolithic. In the 7th millennium BC, Jiahu culture began in China. By the 5th millennium BC, the late Neolithic civilizations saw the invention of the wheel and the spread of proto-writing. In the 4th millennium BC, the Cucuteni-Trypillian culture in the Ukraine-Moldova-Romania region develops. By 3400 BC, "proto-literate" cuneiform is spread in the Middle East. The 30th century BC, referred to as the Early Bronze Age II, saw the beginning of the literate period in Mesopotamia and Ancient Egypt. Around the 27th century BC, the Old Kingdom of Egypt and the First Dynasty of Uruk are founded, according to the earliest reliable regnal eras.