"Namesake of the Bulgarian Khans" can rightfully be considered a monument not only of Slavic, but also of Eastern culture. Having absorbed the language and spirit of the Eastern world, it is still of scientific interest to researchers today. Whose linguistic roots form the basis of the monument: Turkic or Iranian? Here is the question that the author tried to answer in this article. In the 60s of the XIX century, the Slavic scholar A. N. Popov, as part of the chronographic collection of the Russian edition (El-I) - the so - called Hellenic and Roman chronicler-discovered a list of princes, which eventually received the name " Namesake of Bulgarian Khans "(there are 3 lists)1. Immediately after the publication of the source in 1866 [Popov, 1866, p. 25-26], some of the scientists tried to determine the linguistic identity of its mysterious untranslatable passages ("dilom tvirem", "shegor vechem", "vereni alem", etc.). In 1867, the Turkologist V. Radlov came to the conclusion "that these numbers belong to the people who speak the Turkic dialect and that this dialect is very close to the Chuvash" [Kunik, 1878, p.138]. However, the linguistic calculations in Radlov and A. Kunik, who supported him, aroused serious criticism among historians [Ilovaisky, 2004, pp. 490-491, 494], and their author himself admitted "all the unsatisfactoriness" of his research [Kunik, 1878, p.143]. In 1868, the Slavist A. F. Hilferding, who was still unfamiliar with the results of V. Radlov, expressed the opinion that the untranslatable definitions of "Namesake" "have a clear similarity with the words of the Magyar language and related languages of the Ural branch... "[Hilferding, 1868, p. 22]. Almost a century later, this version was supported by the Soviet historian A. Karasik [VI, 1950, pp. 114-118], but it was also not recognized by anyone. Although in the future the Turkic version of the origin of princely names, generic names and untranslatable passages of the source gained more and more ... Read more