First mentioned in 862 Rostov was already quite important and by the 13th century, Rostov became capital city of one of the most prominent Russian principalities. However, in 1474 it was incorporated into Muscovy. Rostov has always been an extremely important ecclesiastic center for the Orthodox Church. From 988 it was the see of one of Russia's first bishoprics. In the 14th century, the bishops of Rostov became archbishops and in the 16th century metropolitans. Rostov was sacked by the Mongols in the 13th and 14th centuries and invaded by the Poles in 1608. The city also saw fierce combat during WWII.