Munda in Early NW India

[David L. White]

        Do the Munda languages have retroflex consonants?  That would surely
be convenient.
        A possible problem with all this is that when non-IE loan-words
start showing up in Sanskrit, they are (as far as I know) Dravidian.  My
impression is that, if there are Munda loan-words, they are few and far
between.
    Speaking of such matters, is there any convincing scenario for how the
retroflex series became phonemic in Sanksrit from internal causes alone?

Dr. David L. White