To this very day, debate among historians continues concerning the critical points in the relations between Russia and the Byzantine Empire and the truth of four important points in Russian history: (1) Russia's political origins, (2) the extent of Byzantine influence on Russian society, (3) the impact of the Golden Horde on Russo-Byzantine relations, and (4) the prevalence of the “Third Rome” theory in the rise of Muscovite Russia--how this led to the Western interpretation of Russian expansionism during eighteenth- and nineteenth-century imperialism and twentieth-century communism. Understanding Russia's Byzantine-derived cultural and religious heritage yields a clearer understanding of Russia's place in the world today. The focus of this thesis is on the extent of the political, religious, and cultural impact of the Byzantine Empire on Medieval Russia and the rise of Moscow as the "Third Rome." The advancement of Russian self-identification as the center of Orthodoxy after the Turkish invasion of Constantinople will also be investigated. Different historiographical perspectives ranging from the opinions of Western, Soviet, and Russian historians take into account the original documents of the Byzantine and Russian medieval Orthodox Church, the Russian Chronicles, and the testaments of Russian princes and tsars.