The best reason to explain why Indian culture is so diverse is because India has been around a lot longer than some of the other countries in the world, including most of the western world. India is also one of the few British colonies to have had a way of life that wasn’t completely wiped out when the British took it over as a colony. This means that some areas show a more British influence, while other areas are still very much in touch with their traditional roots.
Another reason Indian culture is so diverse is that there are so many religions that are followed. There’s no state religion. This leaves the people free to choose what they would like to believe. Some common religions in India are Buddhism and Sikh.