What is proof of Indian citizenship if not a passport, Aadhaar or voter ID?

Government stated like Aadhaar and voter ID, passport is also not a proof of Indian citizenship. Indian citizenship is often established through a combination of records. Law states that people born in India between January 26, 1950, and July 1, 1987, can be considered citizens by birth while those born after, should at least have one parent as Indian citizen.