Goryeo was invaded because of the Mongols in 7 important campaigns in the 1230s until finally the 1270s, but was under no circumstances conquered.[117] Fatigued just after decades of fighting, Goryeo sent its crown prince towards the Yuan money to swear allegiance for the Mongols; Kublai Khan approved, and married considered one of his daughters into the Korean crown prince,[117] as well as dynastic line of Goryeo ongoing to outlive under the overlordship of the Mongol Yuan dynasty as a semi-autonomous vassal state and compulsory ally.

Nevertheless the Sui army was lured right into a trap via the famed Koguryŏ commander Ŭlchi Mundŏk, and endured a calamitous defeat with the Salsu (Ch'ŏngch'ŏn) River. It is said that only two,seven hundred of the three hundred,000 Sui soldiers who experienced crossed the Yalu survived to discover their way again, along with the Sui emperor now lifted the siege of Liao-tung Fortress and withdrew his forces to China correct. Yang Ti ongoing to deliver his armies against Koguryŏ but yet again with out achievements, and just before long 슬롯 his war-weakened empire crumbled." ^