I've looked high and low as they say, and I've yet to find any archaeological trace of a migration from the Balkans into Anatolia for the relevant time period. There is, as Dienekes and Bicicleur pointed out, a 2,000 year gap until you get to the Hittites. I definitely think that "migration" to explain Anatolian is a stretch. Nor is there a good explanation for that
4,000 year gap between a migration to the Altai and the presence of Tocharian. In fact, I don't see where they've addressed any of the "clouds" mentioned by Mallory:
http://www.jolr.ru/files/(112)jlr2013-9(145-154).pdf
As I've said before, I also think that much of what's written on the net about metallurgy in connection to the steppe is very simplistic and sometimes just flat out wrong. I very carefully re-read Anthony's book and the information he provides isn't as detailed or persuasive as I expected it to be from the reputation of the book.
In the Dienekes post about this paper he references the Grigoriev books and papers. This is the link to one of them:
Metallurgical Production in Northern Eurasia in the Bronze Age-
https://www.academia.edu/3833400/Me..._в_эпоху_бронзы._Челябинск_Цицеро_2013._660_с
The English language summary begins on page 654.
It contains a lot of good information, although given his writing style it takes a bit of effort to organize the material in your mind. He's very helpful, in particular, in making clear the exact type of metallurgy that is found at each site. After reading the article it seems pretty clear to me that the metallurgy on the steppe was very derivative, and, in addition, it was very rudimentary until very late, into the Sintashta period, in fact. I'd be interested in hearing what the rest of you think about it.
I think the section about the sudden appearance of an advanced form of metallurgy on the Volga, and then the disappearance of metallurgy in that area in the subsequent period is very intriguing.
"The furnace of the Vera Island hasAnatolian analogies. But the most part of cultural features (megalithic tradition, some ceramictypes) point to Europe. However, in this period metallurgy had no further development in theUrals. Soon it degraded. Economy of hunters and shermen did not need it."
Perhaps it marks the appearance of prospectors and metallurgists from the south for a brief period?
Also intriguing are his comments about Yamnaya:
After this ore smelting appeared in the Southern Urals, in Yamnaya culture. Its metalartifacts have an undoubted Circumpontic background and probable connections with the Northern Caucasus, although it is not known where here the smelting came from. The arsenicalloys were absent here, as well as slag. Technology was, probably, very archaic basing oncopper oxides and crucible smelts. But we cannot say now what it was: either regress of Caucasian technologies or borrowing from local Eneolithic metallurgy."
I take that to mean that he feels that the metallurgy on the Steppe was rather primitive, and either was adopted from the Balkan neolithic cultures or Maykop.* If I'm interpreting it correctly, there was then a hiatus...
"Most late in Europe, in the 3rd millennium BC, metallurgy penetrated the British Isles.In Northern Eurasia we have no evidence about smelting in this period, albeit there is a lotof metal in burials of Yamnaya and Catacomb cultures. A single known ore source of thistime was deposits in Ural sandstones. We see no serious technological transformations. But inthe west, in southern part of Eastern Europe, many metal objects were alloyed with arsenic,so they were not connected with the Southern Urals. It was especially typical of Catacombculture, and origin of this metal is unknown.In the late 3rd — early 2nd millennia BC, at the end of the Middle Bronze Age, a burstof metallurgical production started in Northern Eurasia. Its rst place was Sintashta culturein the Southern Urals where metallurgy penetrated from the Near East."
So, can we infer from this that the metal objects in the Yamnaya and Catacomb culture burials were not, in fact, produced by them? That would put a rather different spin on the Yamnaya "Indo-Europeans" and their cultural package. It would also help to explain why there is no advanced metallurgy in early Corded Ware. It might be not only that the movement into Corded Ware areas was before the development of the "Yamnaya metallurgical package", or by related but not actually Yamnaya peoples, but that Yamnaya did not itself have the technological package, but merely bought (?) or traded (?) for the metal goods, and that the advanced metallurgy on the steppe didn't develop until much later in Sintashta (2000 BC) although still sourced from Anatolia. That's also, of course, where there is the first evidence for chariots, although four wheeled war wagons had already appeared south of the Caucasus.
As to the genetics of all this, given all the movement of technology from the Balkans to the steppe attested to even by Anthony (agriculture, herding, metallurgy) and the movement of metallurgical technology from the south into the steppe documented by Grigoriev, it's easy to see how "farmer" type genes
could have been injected into steppe populations. The long awaited paper, by analyzing the changes in the genomes over time, should help to pin down the precise sources. For example, Maykop influcence would only begin in the mid-4th millennium, yes? If a "Near Eastern" type signature shows up earlier on the eastern steppe, then we're looking at gene flow from the Caspian area sort of south to north I would think.
The language issue is more problematical. One interesting aspect concerns the contacts between the Uralic languages and the Karvelian languages and Proto-European. Both the steppe hypothesis and the Anatolian hypothesis have to get over the hurdle of the presence of the Northeast and Northwest Caucasian languages in the Caucasus. That, and the late date for Maykop influence on the steppe is a problem for a hypothesis that Maykop was the Proto-Indo-European urheimat. If a "southern" folk movement of herders, let's say, that influenced the development of Indo-european came onto the eastern steppe, then that would neatly avoid the Caucasian speakers, and it would be older than a Maykop movement.
Ed. * Maykop not Yamnaya