Most historical writing fits into known categories of time, place, and subject matter. This study is somewhat unorthodox. First of all it lies in a no-man's-land between recognized disciplines in the social sciences where histprical economic anthropology is as convenient a label as any. But of the three disciplines represented, its first commitment is to history. It also lies in the small but growing field of comparative world history – “comparative” because it abstracts particular phenomena having to do with cross-cultural trade and looks for similarities and differences; “world” because it tries to avoid a Western ethnocentric outlook, not because it will try to “cover” what went on everywhere; “history” because it is concerned with change over the very long run of time. It is also history because it asks the historians' question, How and why did human societies change through time? But it is also concerned with the kinds of change economists and anthropologists deal with. It therefore borrows from their conceptual toolbags.

Using this combination of attitudes about history and borrowing from other disciplines also exacts a price. This book is not about a number of other things that may be of equal or greater importance. First of all, it is not a history of world trade. It looks at aspects of commercial practice at several times and places between the agricultural and commercial revolutions. In so doing, it contains a thread of development over time, but it does not seek to “cover” all important traders or trade routes.