The land in the hilly flanks is of a sort which people can farm without too much trouble. There is a fairly fertile coastal strip in Palestine and Syria. There are pleasant mountain slopes, streams running out to the sea, and rain, at least in the winter months. The rain belt and the foothills of the Turkish mountains also extend to northern Iraq and on to the Iranian plateau. The Iranian plateau has its mountain valleys, streams, and some rain. These hilly flanks of the “crescent,” through most of its arc, are almost made-to-order for beginning farmers. The grassy slopes of the higher hills would be pasture for their herds and flocks. As soon as the earliest experiments with agriculture and domestic animals had been successful, a pleasant living could be made--and without too much trouble. I should add here again, that our evidence points increasingly to a climate for those times which is very little different from that for the area today. Now look at Egypt and southern Mesopotamia. Both are lands without rain, for all intents and purposes. Both are lands with rivers that have laid down very fertile soil--soil perhaps superior to that in the hilly flanks. But in both lands, the rivers are of no great aid without some control. The Nile floods its banks once a year, in late September or early October. It not only soaks the narrow fertile strip of land on either side; it lays down a fresh layer of new soil each year. Beyond the fertile strip on either side rise great cliffs, and behind them is the desert. In its natural, uncontrolled state, the yearly flood of the Nile must have caused short-lived swamps that were full of crocodiles. After a short time, the flood level would have dropped, the water and the crocodiles would have run back into the river, and the swamp plants would have become parched and dry. The Tigris and the Euphrates of Mesopotamia are less likely to flood regularly than the Nile. The Tigris has a shorter and straighter course than the Euphrates; it is also the more violent river. Its banks are high, and when the snows melt and flow into all of its tributary rivers it is swift and dangerous. The Euphrates has a much longer and more curving course and few important tributaries. Its banks are lower and it is less likely to flood dangerously. The land on either side and between the two rivers is very fertile, south of the modern city of Baghdad. Unlike the Nile Valley, neither the Tigris nor the Euphrates is flanked by cliffs. The land on either side of the rivers stretches out for miles and is not much rougher than a poor tennis court. THE RIVERS MUST BE CONTROLLED