The Northwest has always had a negative connotation in the Vedic tradition. Thus, R. Siddhantashastree (1978: History of the Pre-Kali-Yuga India, Delhi: Inter-India Publications, p.11) writes:
“The valley of the five tributaries of the Indus had always been held as an unholy region because of its occupation by a non-Aryan tribe antagonistic to the civilized Aryans until the time of Sambarana, (...) the king of Hastinapura belonging to the Lunar dynasty. He was the first Aryan to settle in the valley after driving away the aboriginal non-Aryans to a considerable distance.”
What exactly does the 'Vedic tradition' bring to an understanding of this issue? Among whom was the Vedic tradition prevalent? If we are to go by current practice, as defined in the period from 800 AD to the present, the study of the Vedas was restricted to a single small community of endogamous priests, and empowered scholars. We find grisly references to lead being poured into the ears who heard the recital that shouldn't, and poured down the throats of those who recited it that shouldn't. We have a Sankaracharya in modern times, within my own memory, shutting up a woman reciting a passage from one of the Vedas in a welcoming ceremony, on the grounds that these texts were not fit for women to recite.
This was a ghastly coterie of a tiny handful of people - around 2% in southern states, less than 10% in northern states, with a pocket in Jammu, and we are expected to believe that the entire lot of people held some view or the other because it was consistent with 'Vedic tradition', precisely what this collection of bigots kept confined to themselves with jealous zeal?
As I mentioned earlier, one of the hallmarks of the revisionist school of (everything in general, but particularly of) history is their stern disapproval of anything (that means everything) by way of information that is not confined to themselves and their coterie. Unless it is knowledge in Sanskrit, it is not valid; unless it is Sanskrit interpreted by themselves, it is not a valid interpretation. A perfect circular argument.
So we have this mysterious Siddhanta Shastree opining that there was a non-Aryan tribe occupying the valley of the five tributaries of the Indus who were driven away by an obscure king of Hastinapura (Delhi), that king being given the honour of being the 'Aryaniser' of the region.
It is possible that Siddhanta Shastree has adduced a great deal of evidence and a convincing volume of proof about these assertions. This is certainly corroborated by the gradual shift of the centre of gravity of the culture of the migrants from the mountains of the north-west to the Gangetic Valley, by way of Hastinapura and other intermediate locations. We have, however, only Dr. Elst summarising everything into a sentence, and have to be content with that. But then, if we fail to keep the revisionists on our radar screen because they have no publications, no support in academe, no record of painstaking data collection to test a hypothesis and prove or disprove it, then we deserve to die with our own morose thoughts.
To sum up, no historical evidence, merely deconstruction of Vedic text with no links to the ground realities, or even recognition of the ground realities as existing.