My research examines the presence of the Genoese and other Ligurians in the Maghreb during the thirteenth century, and the consequences of their activities for Islamic law. To do this, I bring two very different source bases together. I have read cartularies from two dozen Genoese notaries, spanning the years 1203–1300, seeking evidence of trade and travel in the Maghreb, and for Maghrebi Muslims and Jews active in Genoa. I have built a database to track and analyze the 1,600 acts in which such travel or trade appears. I have also read several dozen legal opinions (fatwas) in Arabic by Islamic legal scholars in the late-medieval Maghreb responding to questions about Christian-made products, worship, and pollution caused by trade items involving wine and other goods. My research shows the high degree to which Islamic legal norms shaped the conditions of Genoese trade and settlement in the Maghreb during the thirteenth century, as well as how important the Maghreb trade was for a wide swathe of Genoese society.