“Anything to Declare?” The Customs House in Mediterranean Trade, 1100–1300

A neglected institution in histories of medieval Mediterranean trade, the customs-house (Arabic: diwān/ Latin: dugana) was a key mediator between foreign and local merchants in the port cities of late medieval North Africa. Between the twelfth and fourteenth centuries, Italian evidence suggests that most Christian merchants visiting North Africa interacted primarily with agents of the customs, rather than directly with local buyers or sellers. The customs-houses of North African port towns directly employed or subsidized dozens of employees, including many with training in Islamic jurisprudence, and became key sites of diplomacy and negotiation between Christians and Muslims. Customs officials claimed to be able to decide which local merchants could sell to foreigners and on what terms. Evaluating notarial documents and treaty evidence, this paper traces the development of the customs-house in Christian-Muslim trade during the High Middle Ages. Understanding this institution helps us properly appreciate the importance of local state actors in organizing and controlling trade, even during the heyday of Italian commercial hegemony in the Mediterranean.