In the thirteenth century, Mongol forces had invaded China and established the Yuan dynasty in 1271. After a series of Mongol invasions, Goryeo eventually capitulated and entered into a peace treaty with the Yuan dynasty, in which Goryeo was subordinate tributary state to China. The Ming dynasty in China had grown extremely powerful during the 14th century, however, and it began to beat back the Yuan forces, so that by the 1350s Goryeo had managed to regain its northern territories and took back the Liaodong region.