When two people or groups of people don't agree about something, they might have a fight or an argument. Sometimes, when one group is stronger or more powerful, they can hurt or even kill the other group. This is very wrong and very sad.
In 1971, there was a big fight in a country called Bangladesh. Some people in Bangladesh wanted to be their own country, separate from another country called Pakistan. But the leaders of Pakistan didn't want that to happen.
So, the leaders of Pakistan sent their army to Bangladesh to try to stop them from becoming their own country. The army was very cruel - they killed many, many people who were just regular citizens of Bangladesh. They also hurt some people very badly and did things that were very mean.
This was called a genocide, which means a big group of people were killed because of who they were. The people who were killed were mostly Bengali people, which is the majority group in Bangladesh.
It was a very sad time for the people of Bangladesh and many people lost their friends and family members. Eventually, Bangladesh did become its own country, but it was a long and difficult fight.