American troops making their way north to Baghdad have been marching through the "cradle of civilization." The plains between the Tigris and Euphrates rivers also supposedly mark the start of the "Fertile Crescent," a strip of agriculturally rich land that runs through the Middle East. Yet TV cameras show little but sandstorms, bone-dry landscapes, and Iraqis crying out plaintively for water. Why isn't the Fertile Crescent more fertile? Why would the earliest societies have sprung up in such an arid, forbidding place?
The land between the Tigris and the Euphrates, south of Baghdad, can be categorized as "silt desert": It is dry, yet very rich from millions of years of river deposits. When the Sumerian civilization, the first in the region, arose in 3,500 B.C., there was a bit more rainfall but not much. So the Sumerians, like every civilization in the area since, had to rely on extensive irrigation systems. In fact, some scholars think that the ingenuity, hard work, and administrative responsibility required to construct a system of canals helped train the Sumerians in state-building.
Because the land is so fragile, civilizations have periodically lost control of it. The Sumerians (who lived near modern Basra and Nasiriyah) gave way to the Babylonians, who lived farther north. They and their successors—the Hellenistic Seleucid rulers, then Iranian Parthians—continued to build huge canal systems. Early Arab rulers kept them going until the 1200s, when the system, which had seen many partial failures, finally collapsed. From the 15th to the 20th century, the agricultural belt from Baghdad to Basra returned to desert.
(In another challenge to farmers, the land to the south of Baghdad also tends to be flat, with a hard subsurface 3 or 4 feet beneath the topsoil. During irrigation, water pools and the subsequent evaporation leave behind salt. This "salinization" can also ruin cropland. The solution is to periodically leave the land fallow.)
Modern Iraq has restored agriculture in its southeast (north of Nasiriyah, for instance), but that area has never fully recovered. Farming thrives around Baghdad, where growers cultivate everything from wheat to dates to tomatoes to tea. Kurdistan, to the north, is quite lush, too.
The rest of the Fertile Crescent—a term coined by University of Chicago anthropologist James H. Breasted in the early 1900s—receives much more rain than the portion the Americans just marched through. The verdant ribbon of land continues into Syria, then down the Jordan River to the Mediterranean. Some scholars even include the rich, but very narrow Nile Valley as part of the crescent, too.
Thanks to Henry Wright, of the University of Michigan, and McGuire Gibson and John A. Brinkman of the University of Chicago.