How can I trace my ancestry in India? I'm a Christian from Kundamkulam, Trissur, Kerala, India. It is said (there are no written evidences) that we once were Brahmins, got converted to Christianity in the 1st century AD (there are records of St. Thomas visiting the place), and got mixed up with Jews settled in local area (Arthat, near the place). Is there any way to trace our ancestry?

I suspect to understand your ancestry that far back, you would have to resort to DNA testing but I have no idea how feasible or informative this would be in the context of south-west India.

The Jewish Virtual Library has an overview of the long Jewish history in India, as does Wikipedia.