In the Heian period, until TAIRA no Kiyomori became the first samurai to become kugyo, the highest rank for both Seiwa-Genji (Minamoto clan) and Kanmu-Heishi (Taira clan) was Shoshii.
平安時代、平清盛が武士として初めて公卿になる以前は、清和源氏、桓武平氏とも正四位を極位とした。