They were highly systematic and oppressive. Castes have been separated for long enough and strongly enough for there to be detectable genetic differences.

Caste is far older than western colonialism. The genetic evidence shows that castes oppression has been enough to suppress intermarriage for millennia:

https://www.livescience.com/38751-genetic-study-reveals-cast...

> Boy how do we even talk about neocolonialism today if there are still people with full on colonialist sympathies holy shit

How do we talk to people who are in denial bout historic oppression?

I'm not I'm saying the British colonial rule made it worse, here is a good summary:

https://www.bbc.com/news/world-asia-india-48619734

and:

https://en.wikipedia.org/wiki/Caste_system_in_India#During_B...