Hinduism is a polytheistic religion. Polytheism is believing in many gods. In this religion they believed that after death you are reincarnated. This is a life after death. It means that you will return to earth after you die only you could move up in the caste system if you have good karma. They believed in dharma as well as karma.
The Caste System
In the caste system you were born to a certain caste. The highest caste was the priest. The lowest caste was the untouchables. They believed that you could move up after reincarnation. To move up in the caste you needed to have good karma. If you had bad karma you wouldn't move up in the caste.
The Amritsar Massacre was when a group of people in India herd what Gandhi was doing and decided to do the same. In this case they had a meeting in a closed place. The military came in and closed off all the doors. When the military asked the group to stop and clear out, they didn't listen. The military started shooting and since all the doors were closed there was no where for anyone to run. they killed woman children and men that day.