Since the SarasvatI, which dries up progressively after the mid 2nd millennium BC is still described as a mighty river in the Rigveda, the earliest h… - Michael Witzel

Nevertheless, in order to bolster his claim for the antiquity of the "Vedic horse (as) a native Indian breed", he connects this dead horse with the Rigvedic one, which is described as having 34 ribs (Rigveda 1.162.18). But, while horses (Equus caballus) generally have 18 ribs on each side, this can individually vary with 17 on just one or on both sides. This is not a genetically inherited trait. ... As for the number 34, numeral symbolism may play a role in this Rigveda passage dealing with a horse sacrificed for the gods. The number of gods in the Rigveda is 33 or 33+1, which obviously corresponds to the 34 ribs of the horse, that in turn is speculatively brought into connection with all the gods, many of whom are mentioned by name (Rigveda 1.162-3). But this is mere philology, not worthy of "scientific" study...

During the Vedic period, there has been an almost complete Indo-Aryanization of the North Indian hydronomy. . . . Indo-Aryan influence, whether due to actual settlement, cultural expansion, or. ... the substitution of indigenous names by Sanskrit ones, was from early on powerful enough to replace the local names, in spite of the well-known conservatism of river names. The development is especially surprising in the area of the Indus civilization. One would expect, just as in the Near East or in Europe, a survival of older river names and adoption of them by the IA newcomers upon entering the territories of the people(s) of the Indus civilization and its successor cultures.... "such names tend to be very archaic in many parts of the world and they often reflect the languages spoken before the influx of later populations" (368-369). ... "by and large, only Sanskritic river names seem to survive" in the Northwest (370). [In the Kuruksetra area,] "all names are unique and new formations, mostly of IA coinage" (377). ...[in] "the 'homeland' of the Rgvedic Indians, the Northwest "we find "most Rgvedic river names . . . are Indo-Aryan, with the possible exception of the Kubha, Satrudri, and perhaps the Sindhu" (373). [These latter, according to Witzel (1999)] "prove a local non-IA substrate.

“The Indo-Aryan influence, whether due to actual settlement, acculturation, or, if one prefers, the substitution of Indo-Aryan names for local ones, was powerful enough from early on to replace local names, in spite of the well-known conservatism of river-names. This is especially surprising in the area once occupied by the Indus civilization, where one would have expected the survival of earlier names, as has been the case in Europe and the Near East. At the least, one would expect a palimpsest, as found in New England, with the name of the State of Massachussetts next to the Charles River formerly called the Massachussetts River, and such new adaptations as Stony Brook, Muddy Creek, Red River, etc. next to the adaptations of Indian names such as the Mississippi and the Missouri. The failure to preserve old hydronomes even in the Indus Valley (with a few exceptions noted above) indicates the extent of the social and political collapse experienced by the local population.” (p 107)