After breakdown of the Ritsuryo system (a system of centralized government based on the ritsuryo code), the Imperial Court imposed duties including labor on territories governed by provincial government officrs and manors through provinical government officers in the name of public duty or yakubukumai (a special kind of taxation on rice levied by the grand shrines).
律令制の崩壊後、朝廷は造内裏役や役夫工米などを名目に国衙を通じて雑役（臨時雑役・雑公事）や一国平均役などを国衙領や荘園などに課していった。