Regarding the genetic origins of the Slavs:
I ran many tests using various samples and the best fitting model that I could create for modern Russians, Belarusians, and Ukrainians used the following sources:
- Latvia Bronze Age
- Sweden Iron Age (Goths)
- Bulgaria Iron Age (Thracians)
- Ukrainian Scythians (Russian Sarmatians gave very similar results).
- Asiatic Uralics with a mix of EHG + Siberian ancestry
In the targets, I added some Iron Age Balts and a couple of early Slavs for comparison.
In the sources, I also included Hellenistic Anatolians to represent any migrants from the Roman Empire, a south Caucasus sample, Medieval Turkic (Cuman), and Mongols (Golden Horde), but these ancestries only appeared sporadically and at noise level (<2%).
Perhaps the forthcoming genetic study will refute my model, but I think this is probably pretty accurate, since it aligns with Slavic linguistic history (e.g. Scythian loanwords) and archaeological history (e.g. Gothic neighbors).