In the 12th century, as a result of the reduction in tax revenue caused by the expansion of the shoen, the Imperial Court was no longer able to pay salaries to high-ranked aristocrats, so it gave these nobles provinces as chigyo-koku (provincial fiefdom), as well as the right to appoint kokushi (provincial governors) and collect taxes.
12世紀に入ると、荘園の増大で税収が減り、上級貴族に俸給を払えなくなった朝廷は、彼らに知行国として国を与え、その国に関する国司の任命権と税収を与えた。