Since the early days of government based on the ritsuryo legal codes, when cloistered government had not yet been formed, the retired emperor had taken the role of the emperor's protector and guardian upon himself as 'the patriarch of the emperor's family.'
院政の形態は存在しなくても律令政治初期の頃から、上皇が「天皇家の家父長」として天皇の保護者・後見者を担ってきた。