His research explores the religious diversity of medieval society and Christian-Muslim relations from Cairo to Samarqand to Constantinople. This work challenges the confessionalization and linguistic balkanization of scholarly study of this region by revealing a more multi-faceted, interconnected, and dynamic past than has hitherto been suspected. He teaches Middle Eastern history from Muhammad to the present, with a particular emphasis on contingency and strategies for managing difference. In all his work, he seeks to help colleagues, students, and the broader public to understand the stakes and to access the resources of the powerful nexus of human experience in the medieval Middle East.