Where did the steppe admixture in ancient Greeks come from?

[Voskos]

Potential candidates:

Ancient Baltoslavs
Ancient Illyrians
Ancient Thracians
Scythians
Ancient Celts
Ancient Ukraine cultures
Dacians
Ancient Armenians
Direct Yamnaya influence

Share your opinion.

[Voskos]

5. However, the Mycenaeans differed from Minoans in deriving additional ancestry from an ultimate source related to the hunter-gatherers of eastern Europe and Siberia6–8, introduced via a proximal source related to either the inhabitants of either the Eurasian steppe1,6,9 or Armenia4,9.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5565772/

[Voskos]

[wvwvw]

The Steppe R1b linage came from Iberia to the whole Balkan peninsula, including Greece. There it met, the J2 and Ev13 linages that were already there.

The Hellenes, Thracians, Celts, hadn’t been formed yet. When they did, they were R1b, J2 and Ev13.