In the last two decades we have genetic data that paints a much more complex picture. India is a fertile land and people have been streaming in (and out) for at least 50,000 years. If people move just 30km
away every generation that is enough to populate the entire land in a thousand years.
No question that it was a British colonist (lawyer) who stated the divergence, and no question the British routinely followed a longstanding practice of "divide and conquer".
Nevertheless I have never believed that this was a malign British effort. I know many people do believe this. But plenty of linguistic and genetic studies (by people not British and not Indian) have shown reasons to believe this theory.
I actually find these results (the ancient roots and long continuity of Dravidian languages) very cool. It appears to be a much tighter link than other old-lineage languages (e.g. Egyptian/Coptic and some Chinese languages).
Do you dispute that a proto-Aryan migration pushed proto-dravidians south in the Indian subcontinent? If so, what do you think explains the geographical distribution of Aryan vs Dravidian languages?
Also the existence of an isolated Dravidian language in what is now Pakistan is puzzling https://en.wikipedia.org/wiki/Brahui_language