India was ruled by Muslims from around the 12th century until 1857, and then by the British till 1947. However, India still has a large number of Hindus. Countries like Indonesia, Afghanistan, Malaysia now have Islam as the dominant religion.
Many countries in Africa that were ruled by Europeans have more Christians than followers of any other religion.
Given that Indians were ruled by Muslims or Christians for 9 centuries, why weren't the Hindus converted to Islam or Christianity?