Starting in the late Heian period, appointment to the bureau became a hereditary privilege of the Wake and Tanba clans, and the Komori family of the Tanba clan achieved a complete monopoly over the position of Tenyaku no kami.
平安時代後期以降、和気氏と丹波氏による世襲となり、典薬頭は専ら丹波氏の小森家が独占した。