India is not homogeneous. Neither are most (all?) countries in Southeast Asia or Sub-Saharan Africa.
Homogenous thus in my opinion is more like a mix of homogeneity of appearance/culture. Indian people largely share the same appearance and culture, so in that regard, they are homogenous. Africans likewise. Whether some sub-groups have their own distinct appearance, or cultural practice, they are largely similar.
As an example, the formation of African states, cutting across traditional tribal lines which resulted in the ethnic cleansing of the Igbo in former Yorubaland/Nigeria.
India has so many complex cases of this that covering it is an essay of its own.
Even Japan, with its claims of being an ethnostate, became one by force of ideology -- force so strong that it seems like common sense even though it was not true then or now.