There is very little reliable information in the historical sources concerning biography of Oleg Ingvarevich Ryazanskii, a prince of the period of the Mongol conquest of the Russian lands and the establishment of the yoke of the Horde. In fact, in the oldest Russian chronicles and in the laater all-Russian annals it is only reported that Oleg, along with other Ryazan princes, went to the river Voronezh to fight the Mongols in 1237, was released from the captivity in 1252, and died in 1258. Based on such data, both Moscow scribes of the 16th century and a number of modern historians came to the conclusion that the prince spent a decade and a half in Mongolian captivity. However, recent opponents to “historiographic myths” offer a revision of such “misconceptions” and paint a biography of the Ryazan prince full of diplomatic schemes and travels. They refer to information from later sources of the fifteenth and late seventeenth centuries. In fact, it turns out that marginal chronicles are secondary, bear traces of editorial changes, or are the result of scribes’ errors. Nevertheless, there is no information about the alleged diplomatic successes of Oleg Ingvarevich in the reports of the papal envoy to the Mongol Empire, Giovanni da Pian del Carpine, who carefully recorded the stay of the Russian princes at the courts of Batu Khan and the Great Khan. The obvious unreliability of information in later chronicles, on the one hand, and the lack of references to the activities of Oleg in foreign sources, on the other, makes us treat this kind of historical reconstructions with irony.