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.
Dilmun
The Dilmun civilization was the centre of commercial activities linking traditional agriculture of the land—then utterly fertile due to artesian wells that have dried since, and due to a much wetter climate—with maritime trade between diverse regions such as the Meluhha (Indus River Valley), Magan (Oman), and Mesopotamia. The Dilmun civilization is mentioned first in Sumerian cuneiform clay tablets dated to the late third millennium BC, found in the temple of goddess Inanna, in the city of Uruk. The adjective Dilmun is used to describe a type of axe and one specific official; in addition there are lists of rations of wool issued to people connected with Dilmun.