Thomas A. Carlson researches medieval religious diversity (Muslim, Christian, Jewish, sometimes Zoroastrian) in the region we now call the Middle East.  His first book was Christianity in Fifteenth-Century Iraq (Cambridge, 2018), and with support from the National Endowment for the Humanities he published the Historical Index of the Medieval Middle East (HIMME, https://medievalmideast.org/), a multilingual reference work online.  He co-edited Christian-Muslim Relations: Primary Sources, volume 1 (Bloomsbury, 2023), and edited and annotated a forthcoming translation of the story of Rabban Sawma and Yahballaha III (a sort of Marco Polo in reverse) to appear with Hackett.  He has published a string of articles on demographic Islamization.  He earned his PhD from Princeton's History Department in 2012, is an Associate Professor at Oklahoma State University, and in 2024-2025 is a Patricia Crone Member at the Institute for Advanced Study (Princeton, N.J.).

When a provincial governor became vizier of Fatimid Egypt in the mid-1130s CE, Muslim elites panicked that the promotion of Bahram, an Armenian Christian, would spark widespread Muslim conversion to Christianity.  Similar concerns were voiced in the 980s as Byzantine armies conquered northern Syria, and again in the 1250s when the Mongols captured Baghdad.  What made medieval Islamization so fragile that Muslim authors worried about its impermanence?  Modern scholars typically take Islamization for granted, at least after the apogee of Abbasid power, and the scholarly consensus still follows Richard Bulliet in regarding non-Muslims as negligible minorities after 1000 CE, yet medieval authors viewed things differently.  This talk explores what we can know about society-wide conversion to Islam in the medieval Middle East, arguing that religious diversity was a pervasive fact of life in the medieval Middle East far longer than scholars have reckoned with, and that this enduring religious diversity impacted many aspects of Islamic history.  These surprising answers do not make the medieval Middle East any less Muslim, but they do provide richer context for understanding the later medieval development of Islam.