active population of peoples, the primitive nomadic peoples. In contrast with the settled folk, the agriculturists, these nomads lived freely and dangerously. They were in comparison lean and hungry men. Their herding was still blended with hunting; they fought constantly for their pastures against hostile families. The discoveries in the elaboration of implements and the use of metals made by the settled peoples spread to them and improved their weapons. They followed the settled folk from Neolithic phase to Bronze phase. It is possible that, in the case of iron, the first users were nomadic. They became more warlike with better arms, and more capable of rapid movements with the improvement of their transport. One must not think of a nomadic stage as a predecessor of a settled stage in human affairs. To begin with, man was a slow drifter, following food. Then one sort of men began to settle down, and another sort became more distinctly nomadic. The settled sort began to rely more and more upon grain for food; the nomad began to make a greater use of milk for food. He bred his cows for milk. The two ways of life specialized in opposite directions. It was inevitable that nomad folk and the settled folk should clash, that the nomads should seem hard barbarians to the settled peoples, and the settled peoples soft and effeminate and very good plunder to the nomad peoples. Along the fringes of the developing civilizations there must have been a constant raiding and bickering between hardy nomad tribes and mountain tribes and the more numerous and less warlike peoples in the towns and villages.
For the most part this was a mere raiding of the borders. The settled folk had the weight of numbers on their side; the herdsmen might raid and loot, but they could not stay. That sort of mutual friction might go on for many generations. But ever and again we find some leader or some tribe amidst the disorder of free and independent nomads, powerful enough to force a sort of unity upon its kindred tribes, and then woe betide the nearest civilization. Down pour the united nomads on the unwarlike, unarmed plains, and there ensues a war of conquest. Instead of carrying off the booty, the conquerors settle down on the conquered land, which becomes all booty for them; the villagers and townsmen are reduced to servitude and tribute-paying, they become