When the starting rank was Jugoinoge (Junior Fifth Rank, Lower Grade) and the highest rank was Shoshii for the leading samurai, Seiwa-Genji (Minamoto clan) and Kanmu Heishi (Taira clan), even those in the lineage of eldest son were not promoted unless there were some deeds of arms.
武門の棟梁である清和源氏、桓武平氏が従五位下を初叙とし正四位を以って極位とされた時代にあっては、嫡流でもいくばくかの武勲がなければ昇ることがなかった。