No understanding of Mesopotamian society is possible without consideration of the extraordinary ecological conditions in southern Iraq both today1 and in the past. Although capable of generating extraordinary wealth, if mismanaged they could and did result in disaster - the widespread abandonment of permanent settlement accompanied by huge loss of life. In permissive environments, numerous political and agricultural regimes are possible, but in constraining environments, like southern Mesopotamia, that is not the case.
The area south of the city of Samarra represents one of the world’s largest deltas, a broad flat expanse of alluvium generated by the accumulating silts of the Tigris and Euphrates rivers that flow through it. The area is so flat that the rivers meander along ridges that rise above plain level, a condition that, without management, results in numerous intertwining branches which are liable to shift with every flood season. Thus the first task of those who established civilization in this area was artificially to raise the levees on either side of the rivers to ensure that a settlement built along one of these channels would not be left high and dry a few years later. Ancient Mesopotamian settlement was built along multiple channels of both the Tigris and the Euphrates with numerous points of connection - a system quite different from that seen today where the Tigris and Euphrates are separate from one another. This multiplicity of interwoven channels greatly limited the ability of political centers to dominate those down-river by threatening to divert water.
These rivers flowed through an area known for its aridity, making irrigation a necessity for agriculture. However, the high river beds made canal irrigation easy - cut a hole in the bank and the water flowed out - and both the archaeological and textual records are replete with evidence for canal construction and use.
All irrigation systems need some management. Canals need to be dug, and if the fields at the end of the system are to continue to receive water, the silt that builds up near the canal mouth as a result of the abrupt drop in water velocity needs to be cleared out on a regular basis. Moreover, in southern Mesopotamia the water table in the area beyond the immediate environs of the rivers is saline and rises close to the surface under conditions of irrigation. This results in progressive salinization of land, rendering it increasingly less arable over time. This process can be delayed by practicing alternate-year fallowing to allow the deep-rooted desert plants to reestablish themselves and drain down the water table, but at least by the late third millennium salinization of land was the inevitable long-term result of irrigation. Such salted-up fields can only recover if they are allowed to revert to desert so that the winds will scour away the salt crust, generating sand dunes.
Irrigated land is and was used in two different ways. Plots close to the main rivers were used as date orchards, with vegetables and other fruit trees grown beneath their canopy. The sweet groundwater in these areas meant that the threat of salinization was averted, making the long-term investment involved in orchard cultivation worth while. By contrast, the areas where the water table was saline were devoted to grain cultivation, mostly wheat in the early days of Mesopotamian civilization, replaced by barley, a more salt-resistant plant, as time went on. Evidence on the economics of agriculture in the 1950s of our era in the irrigated south makes it clear that any system that relies on small, privately owned grain plots lacks the flexibility to be economically viable (Poyck 1962). Then, even as share-croppers gave one-third of their crop to landlords, they gained enough from the benefits of participating in a large managed system to make them significantly better off than small farm owners. The combination of silting and salinization thus means that it is only large systems that can maximize the enormous potential of Mesopotamian grain agriculture.
The areas not irrigated also played an important role in Mesopotamian society. Thickets growing along the rivers could be used for timber and the deserts generated enough shrubs to feed sheep and goats. Desert environments can provide good grazing areas for these animals, and in Mesopotamia where water - the key limiting factor - was never far away, the rearing of sheep was a major activity. Wool was a critical commodity since textiles were Mesopotamia’s major export and played a key role in the economy as southern Mesopotamia needed to import stone, metals, and even large timber for construction.
The last resource area is the marshes, places where water pools up in shallow brackish lakes. Most irrigation districts debouched into small marshes, and much larger ones were located in the south and east. These marshes were the sources for materials critical to life in southern Mesopotamia: fish and water birds were hunted, and reeds were woven into mats, built into roofs, twisted into furniture, peeled to make styluses, and even tied together to make houses and boats.
These three different ecological niches should not be thought of as distinct zones but rather were interlocking. The land is so flat that there are few geographical factors that dictate their location. The site of Nippur was in the midst of a marsh when it was first excavated by the University of Pennsylvania in the 1890s, was surrounded by desert in the mid-1970s and is within the cultivated zone today, and this situation is typical for much of Iraq. When fields became no longer productive, they were allowed to lapse back into desert, while new areas were opened up to agriculture, creating new marshes at the ends of the canals. When irrigation systems expanded, they expanded at the expense of both deserts and marshes, covering one with crops and using up the water that was once concentrated in the marshes, and the reverse took place as they contracted.
The result of this ecological mosaic was the presence of three quite different lifestyles - farmer, marsh dweller, and pastoral nomad. But these should not be thought of as permanent ways of life; it is this instability that is reflected in the fluctuations between centralization and chaos that characterized Mesopotamian history. This was part of everyday life, but must have accelerated at moments of crisis as refugees from failed irrigation or political systems sought new ways of survival in the deserts and marshes, and also at moments of centralization when new opportunities lured people into the cities. The written record is full of examples of those with more nomadic backgrounds moving into the cities, but less eloquent on the out-migrations of those who gave up their mud-brick houses for reed huts or tents. Our sources, both written and archaeological, come from those with a stable existence and not from those whose lives were nomadic.
The agricultural system was better adapted for management by large institutions than by individual ownership of plots, but this does not mean that it necessarily led to the widespread exploitation of a large downtrodden peasantry. Such a scenario is not possible without absolute control over the means of production, which in agricultural societies means land. But in southern Iraq land is always temporary and mutable, and changes in lifestyle are always a possibility. Thus it can be argued that as complex society developed in southern Mesopotamia, the key to political power was not so much the ability to control arable land but rather to attract the labor for the creation of arable land through building irrigation canals and exploiting the land (Stone 1997). With time, even when the area of control was extended beyond the cultivated zone, competition for labor between city-states still prevented excessive exploitation.
World History
