This study introduces two Turkic inscriptions written in Cyrillic on lithic artifacts—one on a mid-14th century casting mold recently found in Bolgar, southwestern Tatarstan, the other on a tablet with uncertain date found in Polotsk, in the Vitebsk Region of Belarus, more than half a century ago. Both are similar in that Turkic speech is rendered in Cyrillic script. We discuss the paleographic aspects, interpret the historical context, and suggest a translation of certain words and expressions. Some of them indicate tribal structure and remnants of pagan (totemic) beliefs. The inscriptions testify to the adoption of Russian culture, especially literacy and religion, not only by immigrants from the steppes to the forest zone (the Lithuanian-Russian State), but also by the steppe and forest steppe Islamized population of the Volga basin living within the boundaries of the Golden Horde. Apart from documenting the knowledge of Russian, the inscriptions testify to the assimilation of Christianity, with which the Russian language was inherently linked.