Russian lands

Originally, the name Rus’ (Русь, Rus) referred to the people, regions, and medieval states (ninth to twelfth centuries) of the Kievan Rus'. In the Western culture, it is better known as Ruthenia from the eleventh century onwards. Its territories are today distributed among Belarus, Ukraine, and a part of the European section of Russia.

One of the earliest written sources mentioning the people called Rus' (as Rhos) dates back to year 839 in a Carolingian chronicle from Francia, the Annales Bertiniani; the Carolingians identified them as a Germanic tribe called the Swedes. According to the Kievan Rus' Primary Chronicle, compiled in about 1113, the Rus' were a group of Varangians, Norsemen who had relocated somewhere from the Baltic region (literally "from beyond the sea"), first to Northeastern Europe, then to the south where they created the medieval Kievan state.

The modern name of Russia (Rossija), which came into use in the 17th century, is derived from the Greek Ρωσία, which in turn derives from Ῥῶς, an early Greek name for the people of Rus'. Rus' as a state had no proper name; by its inhabitants it was called rusĭskaja zemlja () – with rusĭskaja becoming russkaja in Modern Russian –, which translates as "Land of the Rus'". The word rusĭskaja is an adjective: the morpheme -ĭsk- corresponds etymologically to English -ish; -aja marks feminine adjectives (namely, zemlja, "land", is grammatically feminine in Slavic). In similar fashion, Poland is called Polska by its inhabitants, that is, Pol-sk-a, originally being the adjective Polish (land).

To distinguish the medieval "Rus'" state from other states that derived from it, modern historiography calls it Kievan Rus'. Its predecessor, the ninth-century Rus' Khaganate, is a somewhat hypothetical state whose existence is inferred from a handful of early medieval Byzantine and Persian and Arabic sources that mention that the Rus' were governed by a khagan.

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