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.
Slavs
In the Western Balkans, South Slavs and Germanic Gepids intermarried with invaders, eventually producing a Slavicized population. In Central Europe, the West Slavs intermixed with Germanic, Hungarian, and Celtic peoples, while in Eastern Europe the East Slavs had encountered Uralic and Scandinavian peoples. Scandinavians (Varangians) and Finnic peoples were involved in the early formation of the Rus' state but were completely Slavicized after a century. Some Finno-Ugric tribes in the north were also absorbed into the expanding Rus population. In the 11th and 12th centuries, constant incursions by nomadic Turkic tribes, such as the Kipchak and the Pecheneg, caused a massive migration of East Slavic populations to the safer, heavily forested regions of the north. In the Middle Ages, groups of Saxon ore miners settled in medieval Bosnia, Serbia and Bulgaria, where they were Slavicized.