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.
List of ancient great powers
Sumer (or "Šumer") was one of the early civilizations of the Ancient Near East, located in the southern part of Mesopotamia (modern-day Iraq) from the time of the earliest records in the mid 4th millennium BC until the rise of Babylonia in the late 3rd millennium BC. The term "Sumerian" applies to all speakers of the Sumerian language. Sumer (together with Ancient Egypt and the Indus Valley Civilization) is considered the first settled society in the world to have manifested all the features needed to qualify fully as a "civilization", eventually expanding into the first empire in history, the Akkadian Empire.