Jews were welcomed in Poland and unleashed to help the economy. The fact that the Poles of the 13 - 17th century were decent to Jews, doesn't excuse what their descendants, not all descendants of course or perhaps not even the majority of descendants, did to Jews. Its true that the Poles didn't treat the Jews the same way the Spainiards treated the Incas of South America. But you really need to confront the reality of treatment of Jews by many, many Poles.
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from the article: Polish bishop accuses Jews of using Holocaust as propaganda