Trade and exchange in human societies are certainly as old as the first human beings. A search for the beginning of organized trade, however, cannot and probably need not go back beyond the beginning of the agricultural revolution. About 10,000 B.C., the first agricultural communities began to emerge in the Middle East, leading by about 3500 B.C. to the first urban civilization in the river valleys of Mesopotamia. The rich, alluvial soils of the lower Tigris and Euphrates river valleys were ideal for farming, though the region was far too arid for farming without irrigation water from the rivers. The developed irrigation system that emerged in the fourth millennium B.C. included plows and a range of domesticated crops that made it possible to free as much as 10 percent of the population from the necessity of agricultural work. These people could then go into manufacturing, trade, the priesthood, political administration, or full-time military occupations.

This earliest urban society in Mesopotamia was followed shortly by other, similar societies. Early dynastic Egypt had joined by about 3000 B.C. A third riverine civilization flourished in the Indus valley of presentday Pakistan between about 2500 and 1500 B.C. All three of these western Asian or northeastern African societies had so much in common in their technology and in other aspects of culture that historians assume some degree of intercommunication at a very early date.

In China and the New World, agriculture and then urban societies came a little later, presumably with more independent development.