Menden were rice fields that were exempt from the tax determined by the government during the late ancient times to the middle ages of Japan.
Rice fields exempt from Zoeki (odd-job tasks) but not Kanmotsu (tribute goods paid as taxes or tithes) collected by the kokuga (provincial government offices) were called Zoeki Menden
Around the tenth to mid-eleventh century, the Ritsuryo Taxation System of So (rice tax), Cho (tributes [Ritsuryo system]), Yo (labor) and zoyo (irregular corvee), suiko (government loans), kyoyaku (trading tributes) changed into Kanmotsu, which was basically paid in rice, and Zoeki, consisting of Buyaku (labor service) and Zatsumotsu (tributes). Zoeki was originally a per capita tax, but in reality was often taxed on the land. After the break up of the Ritsuryo system, benefits from the government such as Fukomotsu (depending upon the class, position, awards, there were Ifu, Shokufu and Kofu and this made up a large part of the income for the aristocracy and temples/shrines), which were given to the aristocrats and temples/shrines, and Shozeimotsu (shozei, a combination of rice tax and government rice collected by kokuga that were exchanged with other necessities by trade and given) to temples/shrines started to fall into arrears.
This was the time when the actual provincial administrative power were drastically passed from the central government to the kokuga. The Kokushi (officers of local government) struggled to collect Fukomotsu and Shozeimotsu and had to set Benbojo (places that were designated for convenience) within their province and used the crops collected in these fields to pay the taxes. In the eleventh century, Todai-ji Temple had Hakumai Menden, Toyu Menden and Kona Menden within Yamato Province. Furthermore, Kokushi issued Kokushi concessions which allowed shoen (manor in medieval Japan) owned by aristocrats and temples/shrines to be exempted from tax. The shoen with Kokushi Concessions were called Kokumen Sho.
However, the exemption of Kanmotsu required the consent of Daijokan (Grand Council of State), Minbusho (Ministry of Popular Affairs), the exemption that Kokushi could give were in principle only for Zoeki. In 1070, based on the shoen list that Kofuku-ji Temple submitted following the Manor Regulation Acts by Emperor Gosanjyo, about 80% of the Shoen owned by Kofuku-ji Temple in Yamato Province were Zoeki Menden.
Zoekimen was a system where the Kokuga and Kyunushi (temple/shrine, aristocrat) divided Kanmotsu and Zoeki and is also called Hanfuyu. Kendenken (right to survey land) belonged to Kokuga and Kokukendenshi (inspector) would often enter the fields to collect Kanmotsu and the rights of the Kyunushi to the Kokuga were often unstable. In addition, Menden originally did not specify a certain field but was a designation of a certain surface area within a certain region (gun, go, sho) and was an Ukimen (floating concession) without a base. As a result, Menden did not exist together in one region but were scattered throughout the region.
The Kyunushi side collected the scattered Menden in one place and fixed the Ukimen to become Jyomenden (stationary concession) and aimed for a unified control of the land and person who had the cultivation rights.
The Jyomenden of Zoeki Menden strengthened the rights of the Kyunushi and led to the Funyuken (right to refusal of entry of Kokushi), or exemption of tax, changing into the overall control of the Kyunushu of Shoen. After the twelfth century, with the clarification of official manor boundaries due to Shoen improvement, Han-fuyu (a system where Kokuga and Kyunushi shared Kanmotsu and Zoeki) gradually decreased. The collection of Zoeki Menden led to Zoekimengata Shoen and was a transient state of Shoen before complete exemption from tax.
However, it was not that Zoeki Menden and Hanyuchi disappeared completely, but the part of Yosegori of the Shimazu Sho, which was the largest Sekkan-ke (the families which produced regents) Shoen covering Satsuma, Okuma and Hyuga Provinces was still under the governance of the Kokuga and Shoen landlord even in the Kamakura Period. Yosegori was a special case of Zoekimen where Kanmotsu was shared by Kokuga and the landholding families and Zoeki was collected by landholding families. Kendenken was held by landholding families and a Benzaishi appointed by the family collected the Kanmotsu and Zoeki. In this case, Kokuga and Shoen were not necessarily against each other but coexisted.