When the third shogun MINAMOTO no Sanetomo was assassinated in 1219 and the blood line of the MINAMOTO family died out, he was seen as a candidate for shogun because his parents were on MINAMOTO no Sanetomo's mother's side, but he established the Kujo family because his younger brother Yoritsune became shogun.
1219年（承久元年）3代将軍の源実朝が暗殺され源家の血統が絶えた時、父母が源頼朝の外戚だったことから将軍に擬せられた時期もあったが、弟の頼経が将軍になったことから九条家を興した。