Did caste exist before the British, or did they invent it?
Ambedkar had no doubt that caste was old and Indian, not a British import. His scholarly work traced its mechanism and origins deep into India's own past, long before any European arrived, and treated it as a home-grown institution that the country would have to dismantle itself. Blaming the British for caste would, on his account, have been another way of avoiding the responsibility that lay closer to home.
There is a separate modern argument, made by some historians, that colonial rule hardened and fixed caste — that the census, by counting and ranking every group, turned a looser, more fluid set of identities into the rigid schedule of the twentieth century. This is a real scholarly debate, and it is about the shape colonialism gave caste, not about whether caste existed before it. The two claims are often confused in argument, and it is worth keeping them apart.