East Slavs
The Russian geneticist Oleg Balanovsky speculated that there is a predominance of the assimilated pre-Slavic substrate in the genetics of East and West Slavic populations, according to him the common genetic structure which contrasts East Slavs and Balts from other populations may suggest the explanation that the pre-Slavic substrate of the East Slavs consisted most significantly of Baltic-speakers, which at one point predated the Slavs in the cultures of the Eurasian steppe according to archaeological and toponymic references.