About ten thousand ancient burial mounds still stand in the Carpathian Basin and surrounds. Many of these kurgans or tumuli show direct archeological links with the highly mobile Yamnaya culture of the Pontic-Caspian steppe to the east, and may have been built by Yamnaya migrants.
The testing of ancient DNA from the remains in these burials is important, because the results are likely to be informative about the profound genetic, cultural and linguistic changes that took place in what is now Hungary and the Balkans during the Copper and Bronze Ages.
But, alas, probably to the disappointment of some readers, my great prediction is that they're not going to be overly relevant to what happened at this time in Northern and Western Europe, and won't upend the current consensus that the Corded Ware culture (CWC) was the main vector for the spread of steppe ancestry and Indo-European languages into these parts of the continent.
The important thing to understand about the Yamnaya expansion into the Carpathian Basin is that it mostly stopped at the Tisza River. It's true that some archeological cultures west of the Tisza, such as Mako and Vucedol, do show fairly strong Yamnaya influences, but they can't be regarded as part of the Yamnaya colonization of Central Europe. Below is a slightly modified map from Heyd 2011 to illustrate my point.
In fact, four early Yamnaya period samples from one of the few kurgans west of the Tisza have already been published along with the Olalde et al. 2018 paper on the Bell Beaker culture (BBC). And one of these samples, labeled I5117, even represents a male buried in a Yamnaya-like pose. But this is how three of these individuals cluster in my Principal Component Analysis (PCA) of ancient West Eurasian genetic variation.
They sit firmly among other Copper Age and Neolithic samples from west of the Pontic-Caspian steppe. In other words, they show practically zero Yamnaya-related or steppe ancestry. Moreover, both of the males belong to Y-haplogroup G2a-L91, which is yet to be found in any samples from the Copper and Bronze Age steppe.
That's not to suggest, however, that the spread of the Yamnaya culture into the Carpathian Basin was a cultural process with little or no genetic impact. It probably wasn't, because five samples labeled "Yamnaya Hungary" were featured in the Wang et al. 2018 preprint on the genetic prehistory of the Greater Caucasus, and judging by their PCA and ADMIXTURE results (in the figure below from the said preprint) they're not very different from most other Yamnaya samples, such as those from far to the east in Kalmykia or Samara.
But the point I'm making is that not every one of the ten thousand kurgans and tumuli in the Carpathian Basin and surrounds was built by newcomers from the steppe, and, thus, my other prediction is that a fair proportion of the Yamnaya-related burial mounds, especially west of the Tisza, might contain remains without any steppe ancestry.
As far as I know, the Y-haplogroups of the aforementioned Yamnaya Hungary samples haven't yet been reported anywhere. But there are three ancients in the Mathieson et al. 2018 paper on the genetic prehistory of southeastern Europe that are probably highly informative about what we can expect in this context, because based on their archeology and ancestry, they're likely to be closely related to the Hungarian Yamnaya population. They are:
Balkans_BronzeAge I2165: Y-hg I2a-L699 3020-2895 calBCE
Vucedol_Croatia I3499: Y-hg R1b-Z2103 2884-2666 calBCE
Yamnaya_Bulgaria Bul4: Y-hg I2a-L699 3012-2900 calBCE
That's not much to work with, you might say. Perhaps, but keep in mind that R1b-Z2103 has now been reported in Yamnaya samples from Ciscaucasia, Kalmykia, and Samara, and I2a-L699 in a Yamnaya singleton from Kalmykia. Thus, a lot of outcomes are still possible, but some are more likely than others. So I'm expecting most Hungarian Yamnaya males to belong to R1b-Z2103 and I2a-L699, or perhaps even the other way around!
However, in line with my great prediction, I don't expect to see any R1a-M417 or R1b-L51, the two most common Y-halogroups among present-day Europeans living north and west of the Balkans. And I think that if these markers do actually show up, then they'll be represented by nowadays rare or even extinct lineages that aren't very important to the peopling of Europe. Any thoughts? Feel free to share them in the comments.
See also...
Hungarian Yamnaya > Bell Beakers?
Single Grave > Bell Beakers
Dutch Beakers: like no other Beakers