The article presents the generalized data about the first results of radiocarbon dating carried out for the archaeological sites of the Oka Plateau in the Eastern Sayan Mountain Ridge. For the first time archaeological sites in the territory of the Oka Plateau have become known since the beginning of the second part of the 19th century, however at that time only assumption about the ancientry of the sites was proposed without substantiations. Further, for a long time archeologists visited this territory occasionally with long time intervals and the investigations consisted of the collecting artifacts from daylight surface. All attempts of the archaeological site and materials dating was based on the comparing of the typology and morphology of the artifacts from the Oka Plateau and that from the neighboring territories. In 2017 chronological investigations of Oka Plateau ancient sites with using radiocarbon dating metho began. The first archaeological site, which was dated by radiocarbon method, was the stone construction in the form of the pathway that the local people called Strela Gesera. Further on ancient settlements were engaged in the chronological research. Basing on obtained data the fact about ancient people occupying Rivers Valleys of the Oka Plateau in the final Pleistocene was approved.