Well there are tribes in the Andaman & Nicobar Islands of India, where the people there supposedly have African origins, and are completely unrelated to the people living in the Indian mainland.
http://en.wikipedia.org/wiki/Andaman_and_Nicobar_Islands#Name_origins
Joseph Greenberg proposed that these languages, or at least Great Andamanese, are related to the Papuan and Tasmanian languages as members of a phylum he called Indo-Pacific, and especially close to the western branches of Indo-Pacific. This proposal is not generally accepted by linguists (see Extended West Papuan).
The Andaman Islanders are physically Negritos - short-statured, peppercorn-haired, dark-skinned people found in small surviving pockets all over tropical Asia and New Guinea, and perhaps beyond. However, old skulls of unmixed Andaman aborigines display many morphological affinities to crania of the Caucasoid race. Moreover, recent phylogenetic studies of the human Y-chromosome have shown that the Y-chromosomes of unmixed Andaman aborigines are ultimately derived from the same ancient YAP+ clade, Haplogroup D, that produced the Y-chromosomes of about 90% of the Ainu of Japan and about 50% of the Tibetans of Tibet. Interestingly, while all other Negrito groups in Asia proper speak languages closely related to those of their non-Negrito neighbors, Andamanese shows no similarity to the language even of the nearby Nicobar Islands. This has led some to speculate that the Andamanese languages may be the last representative of the (or one of the) original languages spoken by the Asian Negritos throughout Southeast Asia before Neolithic groups took over their areas, leaving them in their current fragmented distribution.