Abstract: PaleoDNA testing is becoming one of the most complex areas of modern biotechnology. Modern technologies make it possible to qualitatively extract DNA and test it by various methods, including the determination of the Y-chromosome haplogroup and mitochondrial DNA. The paper describes the results of determining the Y-DNA haplogroups of two ancient burial sites of the XII-XIV centuries from the middle course of the Klyazma. The data obtained make it possible to determine the Y-haplogroup by the markers identified in the study. The article describes the technology using bioinformatics methods and the result obtained, which with high probability determines the Y-haplogroups R1a-M458-L1029 and I1-Z58. This work summarizes the initial stage of research undertaken in 2019-2020. The first evidence of the presence of R1a-M458 and I1-Z58 among the Klyazma population of Northeastern Russia in the XII-XIV centuries not only supports the point of view of the presence of Y-haplogroup R1a for all medieval Russian lands (inhabited by descendants of Eastern Slavs), but also hints that a certain genetic unity with the western parts of the area of the Slavs may exist (since the most serious concentrations of R1a-M458 and I1-Z58 are observed in the western part of the Slavic area).