Belarus–Ukraine relations
Belarus–Ukraine relations (, "Byelaruska-ŭkrainskiya adnosiny", , "Ukrains'ko-Bilorus'ki vidnosyny", , "Belorussko-ukrainskiye otnosheniya") are foreign relations between Belarus and Ukraine. Both countries were successively ruled by the Polish-Lithuanian Commonwealth, the Second Polish Republic, and ultimately, the Russian Empire. Prior to the 1991 breakup, both countries were part of the Soviet Union as the Belarusian SSR and Ukrainian SSR when they were the founding members of the United Nations in 1945. Being Slavic nations, both Belarus and Ukraine share closely related cultures and are predominantly inhabited by the East Slavic ethnic groups of Belarusians and Ukrainians respectively, along with a few Russians. Today, the two countries share an 891–km border.
Ukrainian language
In the 19th century, the question of whether Ukrainian, Belarusian and Russian languages are dialects of a single language or three separate languages was actively discussed, with the debate affected by linguistic and political factors. The political situation (Ukraine and Belarus being mainly part of the Russian Empire at the time) and the historical existence of the medieval state of Kievan Rus', which occupied large parts of these three nations, led to the creation of the common classification known later as the East Slavic languages. The underlying theory of the grouping is their descent from a common ancestor. In modern times, Ukrainian, Russian, and Belarusian are usually listed by linguists as separate languages.