"Anagenesis: Migration, Conversion, and the Making of History in Judaism, Christianity, and Islam" focuses on periodization, i.e. how space, time, and history are identified, categorized, and privileged in historical narrative. Incorporating insights from Kathleen Davis, Geraldine Heng, Travis Zadeh and Garth Fowden, I explore new approaches to the shared sources and concerns of medieval literary traditions as part of the project of a Global Middle Ages. I propose an alternative paradigm of periodization, which I call anagenesis, to demonstrate how Jewish, Christian, and Muslim communities constructed history through the imagined recovery of a scriptural past and a monotheistic creation. Anagenesis confronts the cultural consequences of religious conversion and mass migration – two major phenomena in the Medieval World. Acts of miraculous re-discovery and re-birth create a new hybrid history of pre-conversion and pre-migration cultural traditions with the idea of a universal monotheistic history that lies before, behind, and beneath communities. In a series of case studies, I explore forms of anagenesis that highlight the exchange of narrative traditions between Jewish, Christian, and Muslim communities, situating Early English literature in this cross-cultural context. I study Beowulf in comparison with other accounts of “pagan” heroes who paradoxically discover religious relics signifying the conversions of their future descendants; I situate Old English and Anglo-Latin accounts of the “Seven Sleepers of Ephesus” within broader collection of legendary figures whose re-emergence after centuries of sleep highlight the distinctions between historical eras; I place the anti-Semitic depictions of “Gog and Magog” in Matthew Paris and Mandeville’s Travels within the broad ambit of narratives about enclosure and escape in Jewish, Christian, and Islamic tradition, highlighting how such ideas provided an outlet of anxieties about migration, invasion, and geographical ignorance. Anagenesis provides a framework for tracing the intellectual discourses across cultural boundaries in the longue durée. It emphasizes how both medieval and early modern thinkers deployed narratives of genealogy and invention to forge claims of cultural continuity across space, time, and different strands of literary tradition.