Slavs
Slavs are the largest ethno-linguistic group in Europe. Present-day Slavic people are classified into East Slavs (chiefly Belarusians, Russians, Rusyns, and Ukrainians), West Slavs (chiefly Czechs, Kashubs, Moravians, Poles, Silesians, Slovaks and Sorbs), and South Slavs (chiefly Bosniaks, Bulgarians, Croats, Macedonians, Gorani, Pomaks, Montenegrins, Serbs and Slovenes).
Ukraine
Poland defeated Western Ukraine in the Polish-Ukrainian War, but failed against the Bolsheviks in an offensive against Kiev. According to the Peace of Riga, western Ukraine was incorporated into Poland, which in turn recognised the Ukrainian Soviet Socialist Republic in March 1919. With establishment of the Soviet power, Ukraine lost half of its territory to Poland, Belarus and Russia, while on the left bank of Dniester River was created Moldavian autonomy. Ukraine became a founding member of the Union of Soviet Socialist Republics in December 1922.