This paper discusses one of the topical issues in Siberian studies, namely, the beginning of the tradition to administer a shert’, an oath of allegiance to Muscovite sovereign, to the peoples of Siberia. Although the historians do not doubt the fact that this practice dates back to the first years of Russian colonization of Siberia, the idea that the oath was administered by Ermak Cossacks, originated by G.F. Miller, cannot be considered conclusive. The author pays special attention to the analysis of Yesipovsky chronicle message of the beginning of such practice at the time of «Siberian seizure». The study revealed that the edvidence mentioned in the chronicle message includes literary clichés available in the Esipov’s work. The message contains the text entry of the shert’ oath record composed not in the second quarter of the 17th century, as it was previously considered, but rather before the death of Kuchum, i.e. in early 17th century. We have proved that Ermak Cossacks limited their control practices to collecting a tribute, while the practice of shert’s oath administered to Siberian outlanders started from the subsequent expeditions of Tsar Fyodor Ivanovich’s governors, I. A. Mansurov and V. B. Sukin in particular. We have found that the first oath-givers were Prince Luguy and Prince Igichey, Tsyngop Murza, and a prominent Tyumen Tatar service man M. Achekmatov.