Moslems have concurred Iberia and ruled very harmoniously for centuries. Many historians note that Christians, Jews, and pagans live quite well under the Muslim rule.
In XI-XV centuries they were rooted out by the Cristian armies. Not that the Christians had any more claim to that land: they, too, invaded Iberia just a few centuries prior to Muslims. But Muslims were rooted out as occupiers.
Jews, on the other hand, came there with the Romans, no later than 1st century BC. They have never occupied or gought againts the Kings --- they never even formed a political entity; they were merely a part of the populaiton of Jewish faith.
They were expelled not as occupiers but as infidels, and Isabella said so herself; namely, that now, with Muslims gone, she wanted her realm to be entirely Christian.
Collaborators are always killed, Bear. Isabella offered the Jews conversion --- precisely because there was not "oppression" of Christians by Jews. Her objective was to have no infidels in the realm, and if Jews converted thaat would suit her just fine. Some Jews did indeed convert, most left. Of the latter, scores have perished by the hand of the rapist and the robber on land and of the pirate on the Mediterranian.
The "collaboration" and "persecution" libel has always been fabricated: most recently one hears that "Jews collaborated with the Communists agains the Poles" (as if Polish Jews were not Polish citizens) -- even that "Jews collaborated with the Nazis." This stupid libel is as old as anti-Semitism itself --- that is why "nobody seems to understand" it.
You should get out from the den more often, Bear.
The Jews were grossly over-represented in Communist movements. This is well documented. The Polish Jews certainly collaborated with the Soviet Communist invaders. This is why the Eastern Europeans hated the Jews. Here is a study of Jewish involvement in the NKVD/Cheka:
http://www.ukar.org/shapov01.shtml
""Jews collaborated with the Nazis.""
Some Zionists collaborated with the Nazis because they hoped that Nazi anti-semitism would make European Jews emigrate to Palestine.
The Christians didn't invade Spain. The people of Spain converted to Christianity. The Muslims on the other hand came as invaders. The Christians, therefore, being the descendants of the native people of Spain had a valid claim to the land, whereas the Muslim Moors, as invaders and oppressors, had no claim to it. The Spanish people fought a long and bloody struggle of 700 years, the reconquest, to take back their land from the Muslim oppressors and in doing so saved all Europe from Islamic rule.