Dear friends:
Liguistic evidence is that Roma left India around 1,000 years ago, during the same events which gave rise to the Shik religion - the beginings of conflict with Moslems along the west coast of India.
I dont know much about Roma violin technique, most Roma violists I know are from Hungrey, where there has been classical training influenceing violin styles, I believe, however, I will ask other friends who may know Roma who play more traditionaly.
As far as Roma not bringing the violin to Europe, maybe, maybe no, but I would not be the one to tell any Roma they did not!
All the best
Larry