The new political relationship-tributary system bet ween the Yuan Empire and the Korean Ki ngdom was very different from those in the Liao ,Song and Jin dynasties . This new system defined the status of metropolitan and vassal states . Through diplomatic intercourses , royal fami lies' exchanges ,imperial exami nations ,traveling scholars ,and the spread of books ,the channel of literary exchanges bet ween the Yuan Empire and the Korean Ki ngdom was broadened . The stable system of metropolitan and vassal states resulted in the flourishing of Korean literature which was influenced by the literature in China proper . This flourishing manifested itself in the explosive increase of literary works and prestigious writers in the late period of the Korean Ki ngdom.The fashion of Korean literature turned fromflowery style ,emulating the poets in the late Tang Dynasty ,to a leisurely and comfortable style ,like Bai Juyi's poemin his old age , then to the style of Su Shi who was admi red andfollowed by many Korean writers and poets .This transformation ,fromemulating the styles of the Tang to Song Dynasties ,reflected the process of the metropolitan and vassal states system.