Which of course is the entire basis of India's claim over Kashmir...the fact that colonial authorities sold it to an Indian king. Of course it goes without saying that you and your ilk will ignore the preceding 1,300 years of Kashmiri independence.
India's claim over Kashmir? What does that mean? For a region to be part of a country, it takes a lot more than a 'claim'. If sufficient number of people of a region want to split of badly enough, they will. History proves that no amount of military power can prevent that. But for that to occur several factors are necessary, such as a strong enough cause for differentiation of the peoples, emergence of honest leaders and absence of conflicting agenda.
In case of Kashmir, none of these are true. The people are not really different from India whether it be by religions or cultural roots; the 'leaders' of the separatist movement are effectively neutralized by non-separatists and finally, there is no unified agenda! Notwithstanding the lack of cohesive and proactive Indian strategy in bringing this misery of Kashmir to resolution (largely due to the spolier role played by Pakistan), therefore by history, culture, religion or social norms, Kashmir fits into India. Which is why it still remains there, in spite of our imbecility in dealing with Pakistani mischeif appropriately