An interesting place to look, which, I believe Torsten commented on is Crimea, for the Sindos-Meotians (vel sim). They seem to have IE vocabulary absent from Vedic. Their language also seem lambdic as opposed to Vedic rhotcisms.
The term Sindos, however, seems to me an exonym, perhaps applied to them by peoples who identified them with peoples of the Indus/Sindhos valley.
Has anyone done any serious indepth research on this group?