Question: A boyar was a member of a system that flourished in medieval Europe between what centuries?
Sentence (from "Boyar"): A boyar was a member of the highest rank of the feudal Bulgarian, Kievan, Moscovian, Wallachian and Moldavian and later, Romanian aristocracies, second only to the ruling princes (in Bulgaria, tsars), from the 10th century to the 17th century.
Relevant evidence: Yes