History help

You could try for starters that militant arabs are seen as terrorists and people would want to discourage their presence in certain countries. Could you be a little more specific with your question though, i'm not sure who is prejudicing the arabs and muslims.

People feel that the minorities are ruining their society so some might violently attack the perceived problem. Prejudice usually makes a person feel justified in their actions against a group of people because they think they are helping to reduce the problems in society. That the law and government isn't seeing the problem so now they have to send the message on their own which can lead to hate crimes.