This project will examine Jewish, Christian, and Muslim imaginings about the ten lost tribes in conjunction with the development of Jewish, Christian, and Muslim expectations of the Messiah or messiahs and an anti-Messiah figure, Armilos, the Antichrist, and the Dajjal respectively from the early Middle Ages to the nineteenth century. Scholars have long noted that similarities between Jewish, Christian, and Muslim notions about the messiah and “anti-messiah” developed from early borrowings from one another’s traditions. We maintain, however, that this process of cross-fertilization continued throughout the period under examination and was intimately linked with beliefs about the status, location, and apocalyptic role of the ten lost tribes of Israel. In particular, we argue that the ten lost tribes served as a focus for Jewish, Christian, and Muslim military fears and aspirations against one another, both in immediate, relatively mundane wars, and in the anticipated apocalyptic battles of the eschaton. Tales about the ten lost tribes also shaped medieval and early modern Jewish, Christian and Muslim expectations and even policies regarding the inhabitants of the non-Mediterranean world and guidelines regarding the location and rights of European Jews under Christian rule. Whether engaging in geographical speculation and myths of origin in the non-European and Mediterranean worlds, or expressing fears or hopes about the eschaton, these Jewish, Christian, and Muslim views of the ten lost tribes need to be understood as part of an ongoing dialogue about spiritual and political hierarchy.