Anthropological accounts relate that acquiring resources through trade with neighbors is sometimes a dangerous undertaking that is maybe not far removed from raiding and warfare. "There is a link, a continuity, between hostile relations and the provision of reciprocal prestations. Exchanges are peacefully resolved wars, and wars are the result of unsuccessful transactions" (Lévi-Strauss 1969: 67). Further, Sahlins (1972) observes that reciprocity in trade between unrelated exchange partners in contexts without overarching political control can be a very delicate affair because sometimes it is only the perception of fairness in the exchange that maintains peace.

When people meet who owe each other nothing yet presume to gain from each other something, peace of trade is the great uncertainty. In the absence of external guarantees, as of a Sovereign Power, peace must be otherwise secured: by extension of sociable relations to foreigners - thus, the trade-friendship or trade-kinship - and, most significantly, by the terms of the exchange itself (Sahlins 1972: 302, emphasis in the original).

Yet exchange and markets across boundary areas are common features in world history. Such exchange could consist of "border mechanisms" with trade-partnerships or fictive-kin ties that permit "interactions across tribal boundaries under conditions of peace and personal security" (Harding 1967: 165). Zones between social groups are particularly likely to have active trade and markets if there is some cultural or ecological variation between the groups, such that the products circulating in each zone complement one another (Hodder and Orton 1976: 76). The No-man's-land described as the "Intertribal sector" by Sahlins (1965;1972: 196-204) is a good locale for such exchange because complementary products are available for exchange, and because the morality of exchange in neutral geographical territories permits balanced or negative reciprocity between traders. In perception of value, as well as geography, these border zones can be conceived as overlapping social "spheres of interaction" as described by Barth, where "entrepreneurs will direct their activity preeminently towards those points in an economic system where the discrepancies of evaluation are greatest, and will attempt to construct bridging transactions which can exploit those discrepancies" (Barth 1967: 171). These discussions of the details and great the variability in entrepreneurial strategy anticipate the challenges of an agent-based approach to ancient trade (Adams 1974: 243;Hodder 1982).