These are the principal lines of growth of peaceful barter and traffic; from the right to hospitality and the exchange of women, perhaps also from the exchange of fire, to the trade in commodities. In addition to this, markets and fairs, and perhaps also traders, were almost uniformly regarded as being under the protection of a god who preserved peace and avenged its violation. Thus we have brought the fundamentals of this most important sociological factor to the point where the political means enters as a cause to disturb, rearrange, and then to develop and affect the creations of the economic means.
There are two very important reasons why the robber-warrior should not unduly interfere with such markets and fairs as he may find within his conquered domain.
The first, which is extra-economic, is the superstitious fear that the godhead will avenge a breach of the peace. The second, which is economic, and probably is the more important--and I think I am the first to point out this connection--is that the conquerors can not well do without the markets.
The booty of the primitive victors consists of much property which is unavailable for their immediate use and consumption. Since valuable articles at that period exist in but few forms, while these few occur in large quantity, the “marginal utility” of any one kind is held very low. This applies especially to the most important product of the political means, slaves. Let us first take up the case of the herdsman: his need of slaves is limited by the size of his herds; he is very likely to exchange his surplus for other objects of greater value to him: for salt, ornaments, arms, metals, woven materials, utensils, etc. For that reason, the herdsman is not only at all times a robber, always in addition he is a merchant and trader and he protects trade.
He protects trade coming his way in order to exchange his loot against the products of another civilization--from the earliest times, nomads have convoyed the caravans passing through their steppes or deserts in consideration of protection money--but he also protects trade even in places conquered by him in prehistoric times. Quite the same sort of consideration which influenced the herdsmen to change from bear stage to bee-keeper stage, must have influenced them to maintain and protect ancient markets and fairs. One single looting, in this case, would mean killing the hen that lays the golden eggs. It is more profitable to preserve the market and rather to extend the prevailing peace over it, since there is not only the profit to be had from an exchange of foreign wares against loot, but also the protection money, the lords’ toll, to be collected. For that reason princes of feudal states of every stage of development extended over markets, highways and merchants, their especial protection, the “king’s peace,” often indeed reserving to themselves the monopoly of foreign trade. Everywhere we see them busily engaged in calling into being new fairs and cities by the grant of protection and immunity.