to agriculture; but its periphery—­mountains in the south, steppes in the north—­was inhabited (until a late period, to some extent to the present day) by nomads, who had also been subjugated by the Chou.  The Chou themselves were by no means strong, as they had been only a small tribe and their strength had depended on auxiliary tribes, which had now spread over the country as the new nobility and lived far from the Chou.  The Chou emperors had thus to hold in check the subjugated but warlike tribes of Turks and Mongols who lived quite close to their capital.  In the first centuries of the dynasty they were more or less successful, for the feudal lords still sent auxiliary forces.  In time, however, these became fewer and fewer, because the feudal lords pursued their own policy; and the Chou were compelled to fight their own battles against tribes that continually rose against them, raiding and pillaging their towns.  Campaigns abroad also fell mainly on the shoulders of the Chou, as their capital lay near the frontier.

It must not be simply assumed, as is often done by the Chinese and some of the European historians, that the Turkish and Mongolian tribes were so savage or so pugnacious that they continually waged war just for the love of it.  The problem is much deeper, and to fail to recognize this is to fail to understand Chinese history down to the Middle Ages.  The conquering Chou established their garrisons everywhere, and these garrisons were surrounded by the quarters of artisans and by the villages of peasants, a process that ate into the pasturage of the Turkish and Mongolian nomads.  These nomads, as already mentioned, pursued agriculture themselves on a small scale, but it occurred to them that they could get farm produce much more easily by barter or by raiding.  Accordingly they gradually gave up cultivation and became pure nomads, procuring the needed farm produce from their neighbours.  This abandonment of agriculture brought them into a precarious situation:  if for any reason the Chinese stopped supplying or demanded excessive barter payment, the nomads had to go hungry.  They were then virtually driven to get what they needed by raiding.  Thus there developed a mutual reaction that lasted for centuries.  Some of the nomadic tribes living between garrisons withdrew, to escape from the growing pressure, mainly into the province of Shansi, where the influence of the Chou was weak and they were not numerous; some of the nomad chiefs lost their lives in battle, and some learned from the Chou lords and turned themselves into petty rulers.  A number of “marginal” states began to develop; some of them even built their own cities.  This process of transformation of agro-nomadic tribes into “warrior-nomadic” tribes continued over many centuries and came to an end in the third or second century B.C.