What is a market? Is it a place? a process? a principle? a power? History yields no definitive answers to these questions, partly because the motives of exchange are almost always overdetermined and partly because the earliest markets have left so few records behind them. To be sure, the absence of documentation is scarcely a deterrent for those who prefer to think of markets as the institutional expression of a natural human propensity to truck and barter. If anything, the seemingly magical appearance of markets in the landscape of antiquity tends to confirm this view of trade as a kind of socio-biological tropism, suggesting, as it does, a spontaneous gravitational pull toward commodity exchange encoded deep within the cellular structure of primitive societies. To those economic geographers for whom trade is always an indigenous (or endogenous) development, the map of human settlement invariably resembles a honeycomb grid of marketing areas.