Under Sharia Law in Spain.
Jews were basically 2nd class citizens and Christians 3rd class citizens. In over 500 years of brutal and misery of the islamic occupation.
When the Moors were finally expelled - people were looking for payback.
Just like we saw against Nazi collaborators in France in WWII in modern history.
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They enlisted the help of the Jews to get rid of the Muslims. When that was done, they enlisted Tomás de Torquemada to get rid of the Jews.
The Myth of the Andalusian Paradise by Darío Fernández-Morera
Collaboration against christians and subject populations is old hat. What goes around comes around.