The significance of the horse for the understanding of the distribution of early Indo-European has been much exaggerated. - Colin Renfrew

This hypothesis that early Indo-European languages were spoken in north India with Pakistan and on the Iranian plateau at the sixth millennium ec has the merit of harmonizing symmetrically with the theory for the origin of the Indo-European languages of Europe. It also emphasizes the continuity in the Indus Valley and adjacent areas from the early Neolithic through to the floruit of the Indus Valley Civilization~ point that Jarrige has recently stressed. Moreover the continuity is seen to follow unbroken from that time across the Dark Age succeeding the collapse of the urban centres of the Indus Valley, so that features of that urban civilization persist, across a series of transformations, to form the basis for later Indian civilization. A number of scholars have previously developed these ideas of continuity.

[Supporters of Renfrew’s theory] “have tried to render the Indo-Iranian problem moot. They argue that the Indo-Iranian branch was somehow divided from the main body of Proto-Indo-European before the colonists brought agriculture to the Balkans. Greek and Indic are thus separated by millenniums of linguistic change - despite the close grammatical correspondences between them (... these correspondences probably represent shared innovations from the last stage of PIE).”

As Renfrew put it in his archly-titled review of Mallory’s book – ‘They ride horses, don’t they?’ – the horse has assumed “an almost mythical significance in traditional Indo-European studies” (1989: 845).