I think everyone except few insecure pakistanis consider india as a nation of immense history, culture and diversity.
Pretty much how history — and claim to history works. While many kingdoms existed, the people of India never changed (most stay where they have been since time immemorial). Their identity and heritage doesn’t change. So when india is finally one contiguous area, all their historical and cultural identities coalesce into “Indian history” and that is a their right.
By your logic, no country can claim their ancient history unless they are colonisers
Pakistan hasn’t been very successful in this aspect mostly because you have an Arab fetish, reject your own “pagan” history and then occasionally tries to unilaterally claim all of “Indus Valley civilisation” like a bunch of idiots.