Research objectives: To detect sources and stages for the formation of the concept of the “Siberian Tsardom” in the Russian chronicles and ambassadorial documents from the second half of the sixteenth century. Research materials: This work was carried out on the basis of the analysis of the published sources (chronicles, ambassadorial documents, charters and contracts, travelers’ notes, cartographic data). Results and novelty of the research: In the native historiography, the Shibanid states in the territory of Western Siberia are traditionally referred to as the “Siberian khanate”, terminology which dates back to the famous “Siberian Tsardom” in the Russian sources. An analysis of the written sources and cartography shows that during the fifteenth and first half of the sixteenth century, this notion was not used in any documents in relation to the Shibanids’ possessions. Such terms were most often connected with Tura or East Turan or Tyumen by the Russian authors. As the political interests of the Muscovite rulers expanded east of the Urals, the name “Siberian land” appears in the corresponding sources, which was quite clearly differentiated from neighboring Tyumen for a long time. Only in 1563, during tripartite negotiations of the representatives of the Shibanids, Taibugids, and Ruirikovichi in Moscow, did Siberia start to be connected with the tsardom. This, as well, demonstrates the enlargement of the possessions of Tyumen khans to the east, something which was recognized in the Muscovite State. Afterwards, other names of the Shibanids’ possessions were forgotten and in some cases the concept of the “Siberian Tsardom” or “Siberian Khan” came to refer to some earlier time and to be used for the Tyumen khans, Ibrahim and Kutluk. This reference to the past was created from historical examples which could be used to justify the notion of original Russian possession of the Siberian land. The concept of the “Siberian Tsardom” obviously reflected the interests of particular Muscovite political circles, because it allowed for the consideration of Kuchum Khan as a separatist who seized the throne which was previously in vassal dependence on Moscow, and likewise did not admit his dependence. This latter act legalized and justified the resulting military activities. This concept, elaborated by Moscow diplomats, justified the Siberian khanate being tied into a single category alongside the Kazan and Astrakhan khanates. Their accession could be considered not so much as an unjustified, illegal military aggression, but as an exercise of the right to establish an acceptable form of government for Moscow. The annexation of the Siberian khanate began to be seen as the return of original “fiefdoms” of the Russian sovereign, a right which he received from the old Russian dukes. However, we must understand that the idea of the longstanding tradition of this power was itself developed in Moscow no earlier than the 1570s. Thus, the choice of the name of the “Siberian Khanate (Tsardom)” to define the Shibanid states in the south of Western Siberia reflects the ideology of the Muscovite State from a historic point of view. It had little to do with how its rulers, the representatives of other post-Horde states, and the resident population would call it; for them, the concept of the “Tyumen Khanate” was much closer.