Feudal fragmentation caused the decline of Kievan Rus' in the 12th century. In 1169 Kiev was sacked by Prince Andrei Bogoliubsky of Vladimir; in 1240 it was virtually destroyed by the [[Mongols]] under Batu Khan. The Principality of Galicia-Volhynia continued as the successor state of Kievan Rus' in what was Ukraine until the 14th century, when it was annexed by [[Poland]] and [[Lithuania]]. In the 13th and 14th centuries the Ukrainian people developed a distinct culture from the other East Slavs but language remained the same.
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Feudal fragmentation caused the decline of Kievan Rus' in the 12th century. In 1169 Kiev was sacked by Prince Andrei Bogoliubsky of Vladimir; in 1240 it was virtually destroyed by the [[Mongols]] under Batu Khan. The Principality of Galicia-Volhynia continued as the successor state of Kievan Rus' in what was the Ukraine SSR until the 14th century, when it was annexed by [[Poland]] and [[Lithuania]]. In the 13th and 14th centuries the Ukrainian people developed a distinct culture from the other East Slavs but language remained the same.