The main topic of this paper focuses on the interdependencies between the 16th century historian’s craft and the legendary origo gentis. Two specific examples would be analysed: Marcin Kromer’s Sarmatian origine of the Poles and Nicolaus Petreius’s Cimbrian origine of the Danes. The general presentation of non‑political and non‑ideological presumptions for accepting the mythical past known from the medieval texts delivers the background on which it can be grasped, how Early Modern historians treated that tradition. The analysis of the working methods would be also preceeded by showing the variety of approaches observed in terms of the topic: when dealing with the ethogenetic theories, the historians decided to use polemical oration/treatise as the main form. Another form: the legendary history was applied for presenting the past “before” and “after” the process of shaping the nation/state. The scholarly methods used by both historians included both tradition and novelty: ethymological deductions, endorsment of the classical authorities (and obviously, the Bible), forgery, but at the same time impressive erudition and attempts to addopt some historical criticism.

The study focuses on one of the ways to express for eignness of ethnicities encountered by the inhabitants of Medieval Rus’, namely on constructing the origin of those ethnicities. The narrative about the origin of an ethnicity and its ancestors (origo gentis) is known from European medieval historiography in general. The oldest Russian chronicles, however, are distinguishable for not only recording the origin of their own nation, but noting the roots of completely different cultures, i.e. steppe tribes and northern peoples; later the origin of Mongols is refl ected in a similar way. The comparison of the Primary Chronicle and Latin Central European chronicles which were created almost at the same time period (Chronica Boemorum by Cosmas of Prague, Chronica et gesta ducum sive principum Polonorum by Gallus Anonymus and a slightly younger anonymous Gesta Hungarorum) demonstrates that the primary function of Latin origo gentis was to define the identity of the medieval gens, which was changing into natio of the High Medieval Period, and to legitimate its political structures. In these chronicles, origo gentis never became a separate theme in relation to other nations. On the contrary, the authors of the oldest Russian chronicles considered the identifi cation of the origins of the foreign nations to be the key for recognizing their functions not only in the present or in the past, but, first and foremost, in the future, in the end time.