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
During the Khazar period, the territory of Ukraine was settled by Iranian (post-Scythian), Turkic (post-Hunnic, proto-Bulgarian), and Uralic (proto-Hungarian) tribes and Slavic tribes. Finally, the Varangian ruler of Novgorod, called Oleg, seized Kiev (Kyiv) and established the political entity of Kievan Rus'. Some theorists see an early Ukrainian stage in language development here; others term this era Old East Slavic or Old Ruthenian/Rus'ian. Russian theorists tend to amalgamate Rus' to the modern nation of Russia, and call this linguistic era Old Russian. Some hold that linguistic unity over Rus' was not present, but tribal diversity in language was.