Kingdom of Goryeo
Vassals to the Jurchen Jin DynastyKaesong, North Korea
in 1125 Jin annihilated Liao, which was Goryeo's suzerain, and started invasion of Song. In response to the circumstantial changes, Goryeo declared itself to be a tributary state of Jin in 1126. After that, peace was maintained and Jin never actually did invade Goryeo.