threatening environment. Once these structures were built, however, they themselves constituted an important part of the setting to which peasants had to adjust. The yü-chai, we have seen, came to assume both marketing and administrative functions in rural Huai-pei. Furthermore, the very physical presence of these walled communities had an important effect upon collective survival strategies in the area. Although they were products of human activity, the forts became, in a real sense, a feature of the Huai-pei ecosystem.* As such, yü-chai were an important weapon for predators as well as protectors. Operating on such flat terrain, Huai-pei bandits found the walled fortress a useful substitute for the swamp marsh or mountain lair that their brethren in other geographical regions chose as home base. Just as the construction of fortified communities was an essential method of protection against bandit attack, so the occupation of these same fortifications became a key tactic for successful banditry in Huai-pei.
There was a kind of dialectic at work in the relation between the predatory and protective strategies of survival. On the one hand, the two strategies were polar opposites. Predation was an aggressive attack upon the resources of others; protection was its direct countermeasure. On the other hand, these approaches implied a mutual dependency in which they simultaneously presupposed and limited each other. Although the strategies were fundamentally antagonistic, they provided opportunities for cooperation as well as competition. At times, one mode would pass into the other--militias turned to plunder or bandits____________________