In the thirteenth century the Mongols had conquered Kievan Rus, the medieval Slavic state that included most of present-day Ukraine, Belarus, and part of northwest Russia. For two hundred years the Mongols forced the Slavic princes to submit to their rule. The princes of the Grand Duchy of Moscow, a principality within Kievan Rus, became particularly adept at serving the Mongols. Eventually the Muscovite princes were able to destroy the other princes who were their rivals for power. Ivan III (r. 1462–1505), known as Ivan the Great, greatly expanded the principality of Moscow, claiming large territories in the north and east to the Siberian frontier.

By 1480 Ivan III was strong enough to refuse to pay tribute to the Mongols and declare the autonomy of Moscow. To legitimize his new position, Ivan and his successors borrowed elements of Mongol rule. They forced weaker Slavic principalities to render tribute and adopted Mongol institutions such as the tax system, postal routes, and census. Loyalty from the highest-ranking nobles, or boyars, helped the Muscovite princes consolidate their power.

Another source of legitimacy lay in Moscow’s claim to the political and religious inheritance of the Byzantine Empire. After the empire’s capital, Constantinople, fell to the Ottomans in 1453, the princes of Moscow saw themselves as heirs of the Byzantine caesars (emperors) and guardians of the Orthodox Christian Church.