As for the origin of bushi, the theory that the class of emerging local lords were armed because of a need for self-defense was traditionally mainstream, but recently a theory proposed that its origin is the warrior status which consisted of the military aristocrats such as Seiwa-Genji (Minamoto clan) or Kanmu-Heishi (Taira clan) or lower-ranking government officials and they were linked with the owners of shoen (manor in medieval Japan) or kokuga from the formation period of shoen koryo sei (the system of public lands and private estates) and developed into the managers of the shoryo (territory).
武士の起源については、従来は新興地方領主層が自衛の必要から武装した面を重視する説が主流であったが、近年は清和源氏や桓武平氏のような軍事貴族や下級官人層から構成される戦士身分が起源であり、彼らが平安後期の荘園公領制成立期から荘園領主や国衙と結びついて所領経営者として発展していったとみる説が提唱されている。