Many people have commented in past on "fragility" of the Idea of Indian Nationhood, or looked at it as a "nation of nations" with various sub-nationalities living in India. Some even consider the British to be responsible for uniting India.
Was the Idea of nation hood born in Europe? At best we can say that the European Idea of nationhood was born in Europe certainly not the Indian Idea of nationhood. I am sure nobody will dispute that Indian Subcontinent is historically one civilization. If we look at pre-Islamic period then perhaps the geographic reach of Indian civilization was no less than from Afghanistan in the west to Indonesia in the east. The Idea of Bharat Vasha predates any foreign colonization of India and geographic extent was well understood to be from the mountains to the seas which pretty much covers the present territorial extent of India. Culturally India was united quite early in History. We have to consider the puranic references for this. Let me state a very common reference which is the story of Sati. When Shiva carried Sati's corpse on his shoulders around the world threatening to destroy the universe, Vishnu in order to save the universe from destruction cut the body of Sati into 51 pieces. Each location of the fallen piece is revered as a Shakti Sthal. Please look at the locations of the 51 Shakti Sthal. That is cultural geography of India. It covers entire subcontinent including Pakistan, Nepal, Bangladesh and Srilanka. The majority of these sites are of course in India.
When Adi Shankara traveled across India debating Indian philosophy in 8th century AD he was obviously not prevented from entering at any of the "political" kingdoms from Kashmir to Kanyakumari nor was he ever considered an outsider preaching "local" population. He established the various maths across India and the 4 sacred Dhams in 4 directions. There is no question on the geographical extent of India.
The British were also not the first to politically unite India. We anglicized Indians conveniently forget the local tradition of a "Chakravarti" emerging time and again to politically unite India which was already geographically, culturally and perhaps economically one. Alexander's invasion of India triggered the revival and establishment of a pan-India Chakravarti. Mauryan empire covered India from frontiers of Afghanistan to almost the deep south of the peninsula. Harsha's empire, Gupta empire,Prithvi Raj Chauhan's failed attempt, Mughal and Maratha empires politically united India much before the British. One must understand that political unity requires communication technology. Which nation in the world as large as India could have been politically one without such communication?
I would like to submit that the last such political unity of India was achieved when the Integration of Indian states was undertaken in post partition India. Our constitution is the latest indigenous Chakravarti India has seen and serving and protecting this Chakravarti is every Indian's duty.
I wish public figures would shun this illogical Idea of India being an unnatural nation which ignore the achievements of Indian Civilization and culture going back several millennia.