Grand Duchy of Moscow
Who regained Russia's independence and took the title of "Grand Duke of all the Russias"?
Russia
The most powerful successor state to Kievan Rus' was the Grand Duchy of Moscow ("Moscovy" in the Western chronicles), initially a part of Vladimir-Suzdal. While still under the domain of the Mongol-Tatars and with their connivance, Moscow began to assert its influence in the Central Rus' in the early 14th century, gradually becoming the main leading force in the process of the Rus' lands' reunification and expansion of Russia. Those were hard times, with frequent Mongol-Tatar raids and agriculture suffering from the beginning of the Little Ice Age. As in the rest of Europe, plagues hit Russia somewhere once every five or six years from 1350 to 1490. However, because of the lower population density and better hygiene (widespread practicing of banya, the wet steam bath), the population loss caused by plagues was not so severe as in the Western Europe, and the pre-Plague populations were reached in Russia as early as 1500. Led by Prince Dmitry Donskoy of Moscow and helped by the Russian Orthodox Church, the united army of Russian principalities inflicted a milestone defeat on the Mongol-Tatars in the Battle of Kulikovo in 1380. Moscow gradually absorbed the surrounding principalities, including the formerly strong rivals, such as Tver and Novgorod. Ivan III ("the Great") finally threw off the control of the Golden Horde, consolidated the whole of Central and Northern Rus' under Moscow's dominion, and was the first to take the title "Grand Duke of all the Russias". After the fall of Constantinople in 1453, Moscow claimed succession to the legacy of the Eastern Roman Empire. Ivan III married Sophia Palaiologina, the niece of the last Byzantine emperor Constantine XI, and made the Byzantine double-headed eagle his own, and eventually Russian, coat-of-arms.