Ghislaine Lydon has written a fine book that develops new insights into the organization of long-distance commerce and the role of law in providing a framework for the conduct of trade in a region in which there was no unifying state structure. On Trans-Saharan Trails draws upon the author's detailed research in Senegal, Mali, Mauritania, and the Wad Nun region of southern Morocco. She has read the commercial and legal documents of the nineteenth-century caravanners and of the Islamic judges and clerics who adjudicated their disputes, and she has returned from her journeys with scholarly wealth.

On Trans-Saharan Trails will interest both specialist and lay audiences. In the first two of seven chapters, Lydon critiques the Western world's geographical division of the African continent: the idea that the Sahara marks a fundamental divide between cultural worlds—between “sub-Saharan Africa” and “northern Africa,” Arabo-Berber North Africa and Black Africa, and Islamic and non-Islamic societies—and she introduces the wide range of sources, both oral and written, that bear upon trans-Saharan history. She surveys a broad range of historical scholarship on the Sahara and its shores and summarizes the longue durée of trans-Saharan trade before the nineteenth century. She organizes her discussion of previous scholarship on a topical basis and thereby provides a useful reference source for a range of trans-Saharan historical matters.

Chapters 3, 4, and 5 are concerned with nineteenth-century trade developments, fueled in part by an expanding availability of paper that allowed for the greater use of trade documents, many of which have survived in the libraries of families involved with the caravan trades. New imported goods, including industrially produced cloth, tea, sugar, and firearms, found buyers throughout the Sahara. Lydon explores the complex trade environment of southern Morocco in which Jews from Guelmim and Arabo-Berbers from the wider Wad Nun region collaborated in long-distance trade into Mauritania, and farther south into Mali and Senegal. And she investigates the organization of the long-distance caravans, some of which numbered in the thousands of camels. She highlights the role of labor—including that of women, who typically stayed in the trade towns—that made caravanning possible.

The book's major contribution to the history of Islamic law is laid out in chapter 6. During the nineteenth century, when a “paper economy of faith” expanded throughout the western Sahara, traders increasingly came to rely upon written contracts to organize and govern their long-distance transactions. Lydon explores in detail the credit, partnership, labor, and lease contracts that were integral to this system of long-distance, cross-cultural exchange. Local Islamic judges and clerics interpreted and enforced these contracts, based upon Maliki law, to the best of their abilities. The author notes that in Islamic law only oral evidence had legal standing, and, in Lydon's view, the fact that paper transactions did not have full legal weight compromised the possibilities for institutional development.

Chapter 7 is an investigation of the trade network in the Wad Nun region of southern Morocco. The author argues that, although the cross-cultural trade network was efficient, there were limits to cooperative behavior that were exposed in the event of commercial loss or in the efforts to sort out and apportion the debts and assets of a deceased trading partner. Here Lydon makes the point that much of our historical understanding of trade networks in Africa has been based upon idealized models of behavior, and that the historical realities were always more varied and complex.

In this pioneering work, Lydon has given historians and legal scholars a window into the commercial complexities of trans-Saharan trade that reached across vast distances and multiple currency zones. She explicates the complexities of the contractual categories and the difficulties of legal enforcement. These are significant contributions to historical and legal knowledge. Owing to the limitations of the evidence, it was not possible to study change over time in the commercial and legal institutions and practices. But she has opened a door to more detailed studies that will likely be taken up by following generations of scholars.

On Trans-Saharan Trails makes an important contribution to African history and by extension to world history. It may stimulate broader comparative research on the commercial and legal cultures of other cross-cultural, long-distance trading communities, such as those established along the overland routes of Eurasia.