Slavs
Slavs can be further grouped by religion. Orthodox Christianity is practiced by the majority of Slavs. The Orthodox Slavs include the Belarusians, Bulgarians, Macedonians, Montenegrins, Russians, Serbs, and Ukrainians and are defined by Orthodox customs and Cyrillic script as well as their cultural connection to the Byzantine Empire (Serbs also use Latin script on equal terms). Their second most common religion is Roman Catholicism. The Catholic Slavs include Croats, Czechs, Kashubs, Moravians, Poles, Silesians, Slovaks, Slovenes, and Sorbs and are defined by their Latinate influence and heritage and connection to Western Europe. There are also substantial Protestant and Lutheran minorities especially amongst the West Slavs, such as the historical Bohemian (Czech) Hussites.
Sloboda Ukraine
After the establishment of the Soviet Union Sloboda Ukraine was divided between the Ukrainian SSR and the Russian SFSR. The early 1930s forced end to Ukrainization in the parts of Sloboda Ukraine located in the Russian SFSR led to a massive decline of reported Ukrainians in these regions in the 1937 Soviet Census compared to the 1926 First All-Union Census of the Soviet Union. The Ukrainian SSR reorganized their part of the region several times before establishing the borders of present-day Kharkiv Oblast in 1932.