Abstract: The paper describes the results of determining the haplogroups of two ancient burials of the 12th century from the middle reaches of the Klyazma. The data obtained make it possible to determine the Y-haplogroup and mitohaplogroup using the markers identified in the study. The article describes the using of bioinformatics methods and the result obtained. The result with a high probability determines the Y-haplogroup I1-Z58 of burial No. 26 and the mitochondrial haplogroup H1-146C (highly probable, H1m1) of burial No. 25. This work summarizes the initial stage of research undertaken in 2019-2020, and continued in other works by the team of authors. Some of the results have been published; mitoDNA from burial No. 25 is published for the first time and completes the series of DNA data from the described group of burials from ancient Klyazma settlements, published by the authors earlier. Modern technologies make it possible to extract DNA and test it using various methods, including determination of the Y-chromosome haplogroup and mitochondrial DNA. The article presents the results of the study conducted in 2019-2020 years. The first evidence of the presence of mitochondrial haplogroup H1-146C (burial No. 25) and Y-haplogroup I1-Z58 (burial No. 26) among the Klyazma population of North-Eastern Russia in the 12th century not only confirms the presence of Y-haplogroup H1 in medieval Russian lands (inhabited descendants of the Eastern Slavs), but also indicates that some genetic unity with the western parts of the Slavic area might exist that time.