And by that, I mean there must be an area at least the size of Kerala where the plurality of the population is Jewish. That can be the result of colonisation ("Ship the bleedin' Jews over there to subdue the natives for us") or of Alternate Zionism Tee Emm ("Egad, this hidden verse in the Torah says that Canaan was actually in Delhi! How did we not notice this?", etc.) or of any more imaginative process that strikes you.
Extra points if the POD is in the last 500 years, and super-mega points if you can formulate an Ancient Hebrew Empire that has trading colonies in India.