But Spain is a good place to start. Let's get a slightly less fanatic (or more insane) Queen, or more convincing jewish couriers, and instead of a 1492 explusion outside Spain they are spelled to, say, Extremadura or the islands of Majorca or Sicily. Cue sometime down the centuries, the age of Revolutions, and said island, now with a huge jewish mayority, gains independency -an island would probably find that easier to accomplish-
A similar chain of events could happen with the other mayor jewish expulsion, Englain in, damm, 1214? Thereabouts.
(damm... now I am thinking of zionist Eire... celebrating Chanukka with green beer)