Sometimes people believe in different things and this can cause problems between them. In this case, Buddhists are people who believe in a religion called Buddhism, and Christians believe in a religion called Christianity.
There have been times in history when Christians have treated Buddhists badly and this is called persecution. Persecution means treating someone badly because of their beliefs or ideas. This is not a nice thing to do because everyone should be able to believe what they want without being hurt or treated unfairly.
When Christians persecuted Buddhists, they did things like harm them physically, take away their homes, destroy their religious temples, and even kill them. This was not fair or kind, and it is something that we want to avoid happening in the world.
It's important to remember that everyone has the right to believe in what they want and it's important to treat everyone with kindness and respect, even if you don't agree with their beliefs.