No JS,
it is not so simple as you say a chronology of events.
You know that Adi Shankara went and debated with Buddhist theologists and made peace but do you know how the change exactly reflected over the whole country.
what we kept and what we gave up,who did,when they did and why?
The its and bits of information is not complete enough to make a definitive conclusion.
I personally find the IVC getting unecessary focus.
One more thing,the North west is the only land route to enter the peninsula,the other one is from the east through Bangladesh and even there the land is excellent to settle down and not as bad as in the north west.
So,whats the big deal?
local religion/customs/rituals are as much the face of Hinduism as the vedas & upanishads are.
Far from debating with Buddhist theologians and 'making peace', Shankaracharya reinstituted a robust and unforgiving form of Hinduism, and challenged every tenet of Buddhism. The compromises that you seem to be referring to, the inclusion of the Buddha in the Dasavatara (in some places, not in others), for instance, the adoption of tantric practices into Hinduism, the cross-references to Buddhist Bodhisatvas and to evocative Shakti representations in very late Hinduism, all were local compromises, not changes effected uniformly throughout the country. Some parts of the country responded more readily to the Hindu re-conquest, other parts resisted longer. Bengal held out until the Turkish invasion totally demolished the still-existing great universities of the north Bihar/north Bengal region. These universities were already under pressure from reformist Hindu dynasties such as the Senas, and had lost imperial patronage that they enjoyed under the Palas.
Details of this process of challenge and response between the Hindu revivalists and the remnants of the Buddhist religious structures are available for each region of India in detail, and will prove difficult only for those who have neither a professional nor an amateur knowledge of the subject. I do not know what you refer to as 'its and bits' of information, considering that the bulk of Indian history in any case consists of such 'its and bits' of information, up to and including the magnificent empire of the Mauryas (the Gupta Empire is rather better understood).
Your second, wholly unconnected point was about the IVC. You say that it is getting unnecessary focus. You may well be right, if you are considering the broad sweep of Indian history. However, what that view overlooks is the central part that the IVC plays in myth-building by those seeking to create an alternative ancient history for what is today Pakistan, an ancient history pre-dating Muslim dynasties which is distinct from the ancient history of other regions that now constitute India. This quest has little to do with history, or with archaeology, or with pre-history, and has everything to do with the politics of identity.
The other reason for the unnecessary focus on the IVC is the urgent need for Hindu revisionists to prove that Indian knowledge of India is not entirely a derivative of western research and scholarly studies, but has the potential for an independent, indigenous basis. In order to prove this non-existent indigenous base of knowledge, Hindu revisionists have attacked anything and everything emanating from western scholarship, including any hint that elements of Hinduism might not be entirely indigenous to India from beginning to end, or that any differences exist in the Indian population today, or existed in the past. This effort is partly based on a denial of the AIT, and the promotion of a highly speculative OOI (Out Of India) theory; an inclusion of the IVC into the broad stream of Indian history, in the teeth of the evidence that shows that little, if any, of the major aspects of that civilization were incorporated into succeeding cultures and, by inference, succeeding political structures; a strident claim that the IVC has contributed substantially to the development of Hinduism, based on isolated visual examples of symbols that have been used in later Hinduism; a denial of a Dravidian domination of Indian spoken languages until the adoption of Indo-Aryan languages through north India, and a number of such initiatives.
Not one of them has been accepted by historians in India or elsewhere, but that only fuels the flames of nationalists seeking to make points by distorting history.
Your point about the north-west is quite shallow. It is reported better, certainly, but the east has been as great a source of immigration as the north-west. Whole cultures, civilisational adjuncts to mainstream Indian civilization have grown up along those exchanges. Only the overwhelmingly north Indian Gangetic Basin bias in Indian history obscures these elementary facts.
