Since around the 10th century, the tax system consisting of the ancient family registration system and handen shuju sei (a system of periodic reallocations of rice land) stipulated by the Ritsuryo system (a system of centralized government based on the ritsuryo code) had almost collapsed, gradually shifting into the kokushi ukeoi system, which made Zuryo (the head of Kokushi [provincial governors] who was sent to local provinces to administer) undertake tax collection in their provinces.
10世紀頃から、律令制で規定していた古代の戸籍制度・班田収授による租税制度がほぼ崩壊し、現地派遣の筆頭国司である受領へ租税納入を請け負わせる国司請負制へと移行し始めた。