Final answer:
The Crusades were caused by attacks on Christian pilgrims, the desire for trade routes, and political motivations.
Step-by-step explanation:
One cause of the Crusades was that Christian pilgrims were attacked by Seljuk Turks. The Seljuk Turks controlled Jerusalem and other holy sites, and their attacks on Christian pilgrims led to calls for military action. In addition, European merchants wanted spices and silks from the East, and the Crusades provided an opportunity for them to establish trade routes and gain wealth. Lastly, rulers were taxing Christians heavily in the Roman Empire, and some saw the Crusades as a way to divert attention from internal problems and unite their people.
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