Why didn't Christian Western Europe develop significant Muslim minorities in the Middle Ages, in the same way that the same region had Jewish communities, or how the Islamic World maintained Christian, Jewish, Mandaean, Yazidi, Zoroastrian, and Druze minorities? How could Muslim communities flourish in Western Europe north of Spain to the same extent that the Jews did, and would such communities more likely comprise locsl converts or, like Ashkenazi Jews, at least a founder population of migrants (Arabs, Moors, or even Persians from Iberia, North Africa, or Arabia)? When is the earliest such communitirs might develop?