Poland - apex
Jews were generally used as money-lenders in the Middle Ages because Christians were not allowed to lend money. In spite of this, there was still a lot of persecution. This varied by area. Roman rulers, for example, tended to be more lenient than others.
The Jews
Poland
jews.
jews
The people who took refuge in Poland during the Late Middle Ages were Jews form various parts of Western Europe. There is a link to an article on the history of Jews in medieval Poland below.
They were persecuted in Western Europe and moved eastwards to Poland, which was very tolerant in the Middle Ages and early modern times.
Jews
The Jews maintained a high level of literacy during the Middle Ages, and had their own schools, with the goal being universal education. These schools were informally constituted, and were more like home schooling than state run schools of today. The European Jewish community made great contributions in philosophy during the Middle Ages, probably out of proportion to any other group of people.
Theodore L. Steinberg has written: 'Jews and Judaism in the Middle Ages' -- subject(s): History, Intellectual life, Jews, Judaism 'Reading the Middle Ages' -- subject(s): History and criticism, Medieval Literature 'Jews and Judaism in the Middle Ages (Praeger Series on the Middle Ages)'
In Europe, the largest numbers of Jews and Muslims were in Spain. I suspect the number of both in Egypt was probably greater.