Elsewhere, Mallory (1997) complains that the "argument of archaeological continuity could probably be supported for every IE-speaking region of Euras… - James Patrick Mallory

The westward expansion of the Kurgan culture has been mapped with some degree of accuracy: “If an archaeologist is set the problem of examining the archaeological record for a cultural horizon that is both suitably early and of reasonable uniformity to postulate as the common prehistoric ancestor of the later Celtic, Germanic, Baltic, Slavic, and possibly some of the Indo-European languages of Italy, then the history of research indicates that the candidate will normally be the Corded Ware culture. At about 3200-2300 BC this Corded Ware horizon is sufficiently early to predate the emergence of any of the specific proto-languages. In addition, it is universally accepted as the common component if not the very basis of the later Bronze Age cultures that are specifically identified with the different proto-languages. Furthermore, its geographical distribution from Holland and Switzerland on the west across northern and central Europe to the upper Volga and middle Dniepr encompasses all those areas which [have been] assigned as the “homelands” of these European proto-languages.”

If there are any lessons to be learned, it is that every model of Indo-European origins can be found to reveal serious deficiencies as we increase our scrutiny.

While a good case can be made for an expansion of Pontic-Caspian pastoralists onto the Asiatic steppe, and perhaps also into the belt of central Asian urban centres (Parpola 1988), it is still difficult to demonstrate movements from the steppe into the historical seats of the Indo-Aryans and the Iranians of Iran itself.