trace their national origins to the tribal unions of Kievan Rus' and Rus' Khaganate, beginning in the 10th century. They came particularly under the influence of the Byzantine Empire and of the Eastern Orthodox Church. South Slavs from most of the region have origins in early Slavic tribes who mixed with the local Proto-Balkanic tribes (Illyrian, Dacian, Thracian, Paeonian, Hellenic tribes), and Celtic tribes (particularly the Scordisci), as well as with Romans (and the Romanized remnants of the former groups), and also with remnants of temporarily settled invading East Germanic, Asiatic or Caucasian tribes such as Gepids, Huns, Avars, Goths and Bulgars. The original inhabitants of present-day Slovenia and continental Croatia have origins in early Slavic tribes who mixed with Romans and romanized Celtic and Illyrian people as well as with Avars and Germanic peoples (Lombards and East Goths). The South Slavs (except the Slovenes and Croats) came under the cultural sphere of the Eastern Roman Empire (Byzantine Empire), of the Ottoman Empire and of the Eastern Orthodox Church and Islam, while the Slovenes and the Croats were influenced by the Western Roman Empire (Latin) and thus by the Catholic Church in a similar fashion to that of the West Slavs. Genetics Consistent with the proximity of their languages, analyses of Y chromosomes, mDNA, and autosomal marker CCR5de132 shows the gene pool of Eastern and Western Slavs to be identical and demonstrating significant differences from neighboring Finno-Ugric, Turkic, and North Caucasian peoples. Such genetic homogeneity is somewhat unusual, given such a wide dispersal of Slavic populations, especially Russians. Together they form the basis of the "East European" gene cluster, which also includes non-Slavic Hungarians and Aromanians. Only Northern Russians among East and West Slavs belong to a different, “Northern European” genetic cluster, along with Balts, Germanic and Baltic Finnic peoples (Northern Russian populations are very similar to Balts). The 2006 Y-DNA study results "suggest that the Slavic expansion started from the territory of present-day Ukraine, thus supporting the hypothesis placing the earliest known homeland of Slavs in the basin of the middle Dnieper". According to genetic studies until 2020, the distribution, variance and frequency of the Y-DNA haplogroups R1a and I2 and their subclades R-M558, R-M458 and I-CTS10228 among South Slavs correlate with the spread of Slavic languages during the medieval Slavic expansion from Eastern Europe, most probably from the territory of present-day Ukraine and Southeastern Poland. Religion The pagan