Kievan Rus' were important trade routes and connected Scandinavia, Byzantine Empire, Rus' people and Volga Bulgaria with Khazaria and Persia. According to old Scandinavian sources among the 12 biggest cities of Kievan Rus' or Ancient Rus' were Novgorod, Kiev, Polotsk, Smolensk, Murom and Rostov. Through trade and cultural contact with Byzantine Empire, the Slavic culture of the Rus' adopted gradually the Eastern Orthodox religion. Many sources say that Ryazan, Kolomna, Moscow, Vladimir and Kiev were destroyed by the Mongol Empire. After the Mongol invasion the Muscovite Rus' arose, over all this time, western Russia and the various Rus' regions had strong cultural contacts with the Byzantine Empire, while the Slavic culture was cultivated all the time. The elements of East Slavic paganism and Christianity overlapped each other and sometimes produced even double faith in Muscovite Rus'. Alignment with administrative divisions The following Federal districts of Russia are overwhelmingly European: See also North Asia Russian Far East Siberia Kievan Rus' References European Russia Geography of Eastern Europe