According to a legend, Murakami Genji (Minamoto clan) MINAMOTO no Suefusa (or Suekata) was deported to Sayo-so (estate) in Harima Province, and when Ienori, the heir of Norikage UNO who was the descendant of Suefusa (or Sukekata) became the Jito-daikan (deputy jito [estate steward]) in Akamatsu-mura Village, Ienori began to proclaim 'the Akamatsu clan' (Dubious authenticity.)
伝承によると、村上源氏・源季房（季方とも）が播磨国佐用荘に配流され、後裔の宇野則景の嗣子家範が赤松村地頭代官となったことから赤松氏を称した（真偽不明）と言われている。