Medieval Russia, often referred to as Kievan Rus', emerged in the 9th century and was a federation of Slavic tribes under the leadership of the Varangians. The capital, Kiev, became a cultural and political center, fostering trade and connections with the Byzantine Empire. The adoption of Christianity in 988 significantly influenced Russian culture, art, and architecture. By the 13th century, the Mongol invasion led to the fragmentation of Kievan Rus' into various principalities. The Golden Horde ruled over much of the region, impacting local governance and trade. Despite these challenges, the rise of Moscow in the late medieval period set the stage for the future unification of Russia.