During the time of the Crusades

As-salamu 'Alaykoum

I love history and Islam is a religion rich with such a beautiful history. Now someone, who I assumed was non-muslim, said that the crusades were "launched because of muslim tyranny in the middle east". As someone who studies in the western world I understand that a lot of what is historically written is biased (and not just in a religious standpoint, but western history textbooks can be extremely biased... like how they paint Christopher Colombus to be a saint) and changed and I just wished to ask if this was true or not and if someone could tell me a little bit more about these times.
 
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