I was writing about cultural impression. The very forum posts most articles from Eastern Slavic or Polish cultures on its front page.

Territories of Belarus were never in the sphere of Golden Horde domain. Belarus was that part of Rus that was never conquered by Mongols and Tatars. The same can be said about northern part of present day Russia. Ukraine was for a short period of time ~100-120 years. Most of Muscovy was longer. But nomads didn’t settle Russia . Their far post was in Sarai which is just north of Caspian sea.  All nomads wanted is tributes and control of the rulers. It’s like saying population of the Balkans are Turkish  because they were they were under Ottoman rule for more than 500 years.

Religion and other factors didn’t let people to mix in the past.

If you want to talk about genetics, then there’re appropriate topics on this forum. In short Belarusians, who are eastern Slavs, and western Slavs Poles have virtually no east Asian ancestry in comparison to other Slavs including Slavs from the Balkans. That’s easy to show.

Based on Dodecad admixture runs.

Distribution of East Asian admixture

Distribution of west Asian admixture

Distribution east European admixture that has high correlation with Balto-Slavic ancestry.