ENAlfurkan tatarski prawdziwy na czterdzieści części rozdzielony (A Genuine Tatar Al-Furqan Divided into Forty Parts) is a pasquinade on the Lithuanian Tatars written and published in the seventeenth century. Although it was published in Vilnius under the name of Piotr Czyżewski, there is a continued discussion as to who described the Tatars’ history, customs and position by placing them in a broad context, including a historical and legal one. The arguments presented in the Alfurkan he illustrated with examples from the works of ancient and medieval authors, including references to Roman law. The article attempts to answer to what extent those references were done accurately and with understanding. Thus, the article’s author first identifies the ancient legal content present in the Alfurkan; then, he considers the question of what the errors, manipulations and the specific choice of sources say about the Alfurkan’s author. Keywords: Roman law, reception of Roman law, Lithuanian Tatars, Polish polemical literature, Theodosian Code, Islam in Poland, Quran. [From the publication]