Yi Rebellion
Kaesong, North KoreaThe House Yi of Inju married women to the kings from the time of Munjong to the 17th King, Injong. Eventually the House of Yi gained more power than the monarch himself. This led to the coup of Yi Ja-gyeom in 1126. It failed, but the power of the monarch was weakened; Goryeo underwent a civil war among the nobility.