This paper looks at the impact on the two fields of medieval Jewish history and medieval Islamic history over the fifty years since the first volume of A Mediterranean Society was published in 1967. It takes an historiographical approach, asking what new questions have historians of medieval Jewish and medieval Islamic history been able to ask in light of A Mediterranean Society. In what ways has the documentary geniza, especially as known to us through A Mediterranean Society, transformed these two large fields? And what connections between the study of Jewish history and Islamic history has it enabled that did not exist before? Finally, it asks what questions we might imagine asking in the future.