According to tradition the Indian subcontinent was first evangelied by the Apostle Thomas, who is believed to be buried in that land.
Yup, in fact he was the one who evangelized the Chaldeans as well.
Word has it that the Portuguese, when they initially landed in India on a missionary trip, did not know what to make of these people who had been Christian longer than the Portuguese people had been.
I wouldn't push this claim. Western Christianity never recognized this story and the story has been proven to be false.