In many languages, including English, the Ukrainian words "ruskyi" (a historical term) and "rosiyskyi" are both translated as "Russian." This creates confusion, which is not accidental but rather the result of centuries-long information and political policies by Russia aimed at appropriating the heritage of Rus — a medieval state with its capital in Kyiv.

The state of Rus (9th–13th centuries) initially encompassed the territories of today’s Kyiv, Zhytomyr, Cherkasy, and Chernihiv regions of Ukraine, and later included modern Ukraine and Belarus and parts of Russia. The word "Kyivan" in "Kyivan Rus" was added by historians only in the 19th century to clarify. The inhabitants of Rus called themselves "Rusyns," and their language "Ruska." This is confirmed by numerous historical documents, including records from European travelers.

After the Mongol invasion in 1240, the lands of Kyivan Rus became part of the Grand Duchy of Lithuania. There, the Ruska language remained official until the 17th century. Over time, the name "Ruska language" was replaced by "Ukrainian," but this was more an evolution of terminology rather than of essence: "ruskyi" and "ukrayinskyi" were long used as synonyms.

And now — about Russia. Until the 18th century, the territory of modern Russia was known as "Moscovia" (Latin Moscovia, English Muscovy). It arose as a separate principality in the 13th century. The Muscovite principality was formed under strong influence from the Golden Horde — a multi-century state on the territory of the former Mongol Empire — and remained its vassal until the end of the 15th century. In the 16th century, the Muscovite prince Ivan the Terrible began to call himself Tsar, and the principality became a Tsardom.

In 1721, Tsar Peter I renamed the Tsardom of Muscovy to the "Russian Empire." This name is artificial, as is the word "Russia": it was derived from the name of the ancient state "Rus" in its Greek form. With this renaming, Muscovy–Russia sought politically and symbolically to appropriate the legacy of Kyivan Rus. It was a deliberate step intended to legitimize Muscovy’s imperial ambitions. Later, Russia built a false historical narrative of a "line from Kyiv to Moscow," as if Kyivan Rus had been the first stage of Russian statehood.

The greatest falsifier of history was Empress Catherine II. Under her orders in the 18th century, a commission was created to rewrite chronicles: some were destroyed, some edited, and some rewritten from scratch. Thus was born the myth of a single "Russian people" allegedly including Ukrainians, Belarusians, and Russians — a myth that justified the Russian Empire’s territorial claims on Ukrainian and Belarusian lands and the assimilation of their populations.

This myth is still alive today. It became the ideological foundation of the "Russkiy Mir" (Russian World) concept — a neo-imperial doctrine according to which Russia has the right to intervene in the affairs of neighboring countries under the pretext of "protecting historical lands" and "shared culture." This very doctrine underpins modern Russian aggression against Ukraine.

Therefore, distinguishing between "ruskyi" and "rosiyskyi" is not only of historical importance but also political. It helps us understand why Russia is not the heir of Kyivan Rus and why Ukrainians have their own separate historical, linguistic, and cultural identity.