Sheesh, your post contains so many brainfarts that I really think I ought to be paid wages to explain the falsity in each. I'll address a few.
Really? So modern Pakistan is a cultural evolution of the IVC? Here is something you ought to know - being located on the same geographic territory does not in any way mean that one civilization is a descendant of the other. If so, the present Americans could claim to be descendants of Apaches.
The identity of Pakistan as an entity, as a collective, was created deliberately in the 19th and 20th century, by Iqbal and others. There is nothing wrong in that - a people living in a place can choose to adopt a new identity, if they so wish. But don't pretend that the idea of Pakistan is a continuation of the IVC. No, not even remotely. There have been many abrupt civilizational changes there. The arrival of Islam was probably the last major one. It was a complete break from what existed before. Much earlier, the arrival of Vedic tribes (whether from outside or from within) was also a complete change from what existed before. The vedic civilization was NOT a continuation of the IVC. The later hindu ones may have been a continuation of the Vedic one, albeit very different in religion, customs, tradition and language. The Islamic one that came up later was again a complete break from what existed before.
You don't seem to understand what "civilization" or "identity" means in an anthropoligical sense. You are under the mistaken impression that whoever lives in one place is a descendant of any ancient civilization that was unearthed at the same place. All I can say, to put it as simply as possible, is that
you are wrong.
The identity of Pakistan was born in the past two centuries. The identity of USA was formed in the past four or so. The identity of a French people began with the emergence of the Frankish tribes. The idea of a Germanic people...and so on.
In the South of India for example, the identity of a Tamil people or civilization is millennia old. The identity of a Malayali is 800 or 900 years old. And by the way, the Tamil identity is distinct from the previous proto-dravidian identity. The Tamil identity cannot claim to be 5,000 years old just because there was another civilization that long back in that same region.
Again - living in the same place does not mean being the inheritors of all previous civilizations. That would be true only if each subsequent civilization is a natural evolution of the preceding one. That is not the case with the IV to Pakistan. Heck, even the IVC to the Vedic civilization was a clean break, not a gradual evolution. The Vedic civilization was not a continuation of the IVC. The Islamic civilization was not a continuation of the Vedic.
Depends, what do you mean by "yours"? Our national identity? As I said in my first post, that began in 1947, with the establishment of the Republic of India. That is when India came into existence as a nation-state.
Or are you asking about the identity as one civilization? Then there is no single one, the Indian subcontinent has had many civilizations emerging. Even today, different people have different times for the beginning of their collective identity.
As I mentioned before, the Tamil civilization is probably the oldest continuously existing one in India today. The identity of a Tamilian, of "Tamizhakam", is ancient. The Tamilians can rightly claim to be civilizational descendants of the Cholas, Pandyas etc. But all Indians are not inheritors of those civilizations. There are many cultural identities in India. Only the identity as a single nation is common to every Indian.
Yea this just shows your complete, utter ignorance of what you are talking about. Do you even know what "adivasi" means? It means "original dweller", and it refers to people who lived on the subcontinent BEFORE Aryans or Dravidians or anybody else. There are many adivasis, and the very reason they are called so is because they were separate from the Dravidians and others who came later. So your statement that "Ganga India" (whatever te fvck that means) or "Dravid India" contributing adivasis, is a contradiction in terms. The word adivasi itself means someone who lived here before Dravidians (or anybody else).
The Dravidians called some of those adivasis as "Chandalas" in a derogatory way, and they are today calles "Santals". There are also Kols, and a few other Adivasi tribes whose history is completely different to that of the later Indian peoples, including Dravidians.
You really should not throw out terms you don't know.
No matter what your age, there is no shame in opening a history book or two for the first time. Are you really asking what the non-Pakistani parts of India contributed? Let's see, the Cholas, the Pandyas, the Rashtrakutas, the Cheras, the...man, oh man.
There have been splendorous civilizations in South India that were completely different from the ones in North India an today's Pakistan. In the ancient world, the Cholas were one of the richest civilizations, operating from Tanjavur as their capital. Their accomplishments in arts, literature, architecture, learning etc match or even eclipse those of their North Indian counterparts. Know anything about the magnificent temples, the majestic palaces they built? Check out the Brihadeeswara temple to name just one. Their civilization's influence encompassed South India and much of South east Asia. They had the finest naval fleet of the time, which helped expanding their reach.
That was contemporaneous to the Mauryas in the North. Then there have been so many others, and this is just South India I'm talking about.
Ah wth, I can't really expend so much time educating you. As I said before, pick up a history book. Or if you belong to that set of people who do not have the patience or inclination for reading, watch BBC's "Story of India". One of the episodes is entirely devoted to the Southern civilizations of India, including the Dravidian and Tamil ones.
And that's just one part of India that had great civilizations unshared with today's Pakistan. The Pallavas, Satavahanas, Kadambas, Pandyans, Vijayanagara were all civilizations that had nothing to do with today's Pakistan, and they all not only achieved magnificent feats of civilizational accomplishments, but also left their indelible mark on the subsequent people.
(Have you heard the story of the frog living in a well who thinks his well is the world, and refuses to believe there are rivers and lakes and oceans elsewhere?)
Sounds suspiciously like Aamir Khans "clarification' 
