The Cairo Geniza is a cache of texts from an Egyptian synagogue including letters, lists and legal deeds from before 1500, when most Jews lived in the Islamic world. These are some of the best-documented people in pre-modern history and among the most mobile, crossing the Mediterranean and Indian Ocean to trade, study, apprentice and marry. Data science, neural network-based handwritten text recognition and other computational methods are now helping make sense of the texts on a large scale. Students will contribute to an evolving state of knowledge and gain an insider's view of what we can and can't know in premodern history.