The basis of the Mesopotamian economy throughout history until very recent times was agriculture. The alluvial lowlands supported cereal crops, date palms, and legumes, while the steppe areas of the north, west, and east were used for raising livestock. Innovations such as the seeder plow, crop rotation, the use of draft animals, and efficient distribution of water for irrigation purposes led to high yields, which supported population growth. The process of urbanization, which began in the late fourth millennium, led to the systematic and centralized cultivation of the land and high population densities in cities. The dominant mode of production was by large institutionalized households, primarily temples and palaces, although there were times when private ownership of land was more widespread (as in the Old Babylonian period). The agricultural surplus was collected, stored, and distributed to the dependent labor force in the form of rations, which also supported nonagricultural workers, such as craftsmen, bureaucrats, and priests, as well as the elite. Craft production, especially of textiles, con tributed to an exchange economy, as it was a prized export commodity that could be traded for copper and tin, to make bronze, and for silver and timber.
Historical Dictionary of Mesopotamia. EdwART. 2012.