The lower-ranking vassal system originated from the Shugo and Jito system based on shoen koryo sei (system of public lands and private estates) which was the land system after the Heian period, and it consisted of honryo-ando (acknowledgment for inherited estate) where gokenin were appointed to Jito of the territory inherited from the ancestor and military service imposed by Kamakura-dono or the service of Kyoto obanyaku (a job to guard Kyoto) and Kamakura Banyaku (guards of Kamakura), instead of giving a favor by shinon-kyuyo (granting new domains) where Jito was newly given a territory for their deed of valor.
この御家人制は平安時代以降の土地制度である荘園公領制に立脚した守護地頭制に由来し、御家人に対して先祖伝来の所領の地頭に任命する本領安堵、また武功に対して新たに地頭に人目し所領を与える新恩給与による御恩を受ける代わりに鎌倉殿の課す軍役や京都大番役、鎌倉番役を課す奉公によって成立している。