Correction :

All the White / Asian countries have gone through ( either through willed action or through accident ) massive rounds of culling leaving only the ones that are co-dependent stocks of people who are amenable to working together in nation building.

This is lacking in the Indian sub continent either due to resplendent and bountiful conditions for human thriving or something else entirely.

People have not undergone culling anywhere to the same rates and More Importantly for the Correct Reasons.

the BRITS have banished the undesirables to AUSTRALIA NZ SOUTH AFRICA AMERICA and CANADA
the FRENCH have slaughtered scores of people just so that various regions would dispense with their Breton Occitane Provencal Lorraine Franconian Basque Corsican etc languages in favor of FRENCH

thats basically EUGENICS with a different name and methodology.

This stuff hasnt happened in India