What in Russia was called "bylina"?

A bylina (Russian: были́на) is a traditional East Slavic oral epic poem. Byliny songs are loosely based on historical fact, but greatly embellished with fantasy or hyperbole to create their songs. Most historians of East Slavic and Russian folklore believe that byliny as a genre arose during the Kievan period, during the tenth and eleventh century; byliny continued to be composed till about the arrival of the Tatars in the thirteenth century and the destruction of the Old East Slavic civilization. Byliny incorporate elements of history from several epochs into their stories.