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A. The Russian serf system arose as peasants fled to the protection of large landowners to avoid Mongol taxes.
B. Most Russians converted to Islam when the Mongols outlawed the practice of Daoism in Russia.
C. The Russian monarchy was created when the Mongols appointed the first Russian czar in 1258 CE.
D. The Russian language disappeared as Russians adopted the Mongol language and other cultural features.
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The influence of the Mongol invasion on the territories of Kievan Rus' was uneven. Colin McEvedy (Atlas of World Population History, 1978) estimates the population of Russia-in-Europe dropped from 7.5 million prior to the invasion to 7 million afterwards.Centers such as Kiev never recovered from the devastation of the initial attack. The Novgorod Republic continued to prosper, however, and new entities, the rival cities of Moscow and Tver, began to flourish under the Mongols. Indeed, Moscow's eventual domnance of northern and eastern Rus was in large part attributable to the Mongols. After the prince of Tver joined a rebellion against the Mongols 1327, his rival prince Ivan I of Moscow joined the Mongols in crushing Tver and devastating its lands. By doing so he eliminated his rival, allowed the Russian Orthodox Church to move its headquarters to Moscow, and was granted the title of Grand prince by the Mongols. As such, the Muscovite prince became the chief intermediary between the Mongol overlords and the Rus lands, which paid further dividends to Moscow's rulers. While the Mongols often raided other areas of Rus, they tended to respect the lands controlled by their principal collaborator. This, in turn, attracted nobles and their servants who sought to settle in the relatively secure and peaceful Moscow lands. 
Although Russian forces defeated the Golden Horde at the Battle of Kulikovo in 1380, Mongol domination of parts of Rus territories, with the requisite demands of tribute, continued until the Great standing on the Ugra river in 1480.