The "Nobunaga-ki" (Record of Nobunaga) says, 'There had not been the term "umajirushi" until the Eiroku era (from 1558 to 1570), and then some symbols were gradually developed from the Genki era (from 1570 to 1573) and now they are used as a main symbol,' in the Section 15: Umajirushi.
《信長記》十五馬験之事に、〈永禄（1558‐70）ノ比マデハ馬験ト云事ナカリキ、元亀（1570‐73）ノ比ヨリ初リ、次第ニ長ジテ今ハシルシノ要トス〉とある。