Jori sei (system of land subdivision in ancient Japan) (条里制)
Jori sei is a system of land subdivision (management) in Japan from ancient period until the late mediaeval period. The system had a feature to devide a certain area of land into squars with perpendicular parallel lines (hokaku sen [grid lines]) at about 109-meter intervals, and there are remains of jori chiwari (lands allocated using jo and ri) throughout Japan except Hokaido and Okinawa even now.
Mechanism of jori
In many cases, hokaku sen that divide jori are located north-south and east-west directions, but there are quite a few cases in which hokaku sen are at a tilt depending on the regions and geological formations. For example, if the north-south direction is tilted at a 7 degree angle, normally the east-west direction is also tilted so that they are at right angles to each other.
In some cases, hokaku sen are out of alignment in adjacent lands. For example, when the angles of hokaku sen are different by counties, there can be seen clear gaps of jori chiwari at the border of counties on flatlands.
In handen (the allotted farmland) map etc., hokaku sen are drawn not only on rice fields but also on water surfaces and mountainous lands. However, not all areas including those without rice fields were covered by hokaku sen. Hokaku sen were drawn independently in lands with rice fields. Specifying the position of mountains within the area using jori made the positional relationship of rice fields easier to understand.
Basic unit (tsubo)
The basic unit of jori is about 109-meters square (in some cases, diamond shape or rectangle was used). In ancient Japan, about 109 meters were equivalent to one cho (unit) (=60 bu), and the area of about a 109-meter square was also called one cho. This basic unit of one-cho square is called 'tsubo' or 'bo' (it is different from tsubo that is currently used).
Each tsubo is subdivided equally into 10 sections, and these sections were called 'dan' (there were two types of subdivision: nagachi [long land] type and hanori [half-divided] type).
The section in which the basic unit tsubo is aligned 6x6 (in other words, six-cho square) was called 'ri.'
Each tsubo in ri was assigned a number between 1 and 36 and called, for example, ichi no tsubo (there were two types of number assignment to tsubo [tsubonami]: parallel type tsubonami and zigzag type tusbonami).
Jo and ri
For the land divided into the units described above, the horizontal row of ri was called 'jo' and the vertical row of ri was called 'ri,' and from the base point that was arbitrary set, each section could be clearly indicated such as ichi-jo, ni-jo, and san-jo (first jo, second jo, and third jo) vertically and ichi-ri, ni-ri, and san-ri (first ri, second ri, and third ri) horizontally.
Traditionally, jori sei was considered to have been enforced along with handen shuju sei (a system of periodic reallocations of rice fields). Because the area of agricultural land issued to the people (handen shuju) was determined in a single uniform way under the ritsutyo system, a strong relation between orderly jori sections and handen shuju was assumed.
(see also kubunden [rice fields given to each farmer in the Ritsuryo system])
In recent archaeology study, however, while handen shuju is considered to have started in the Asuka period or early Nara period, first appearance of land representation using jori was in 743, the mid Nara period. Because there is a gap of about 50 years, it is assumed that there was no direct relation. As a result, the concept of jori sei itself is under re-examination.
The term Jori sei assumed that both of the following were formed by public system:
Streets and grooves along the one-cho square and regular sections such as nagachi type and hanori type that are seen in the square (jori chiwari)
Representation of lands by sections called jo, ri, and tsubo (jori naming method)
As described above, now it is considered that the system of periodic reallocations of rice fields (handen shuju sei) was not a backing public system of jori sei (a system of land subdivision in ancient Japan) and therefore it came to be thought that there was no backing public system in jori sei.
A term 'plan of jori' is now used as both jori chiwari and jori naming method, and as the name of the land representation system in which they are combined apart from public system.
Process of formation
As described above, the theory to seek the origin of plan of jori in handen shuju sei is virtually rejected. The current widely-accepted theory is that rapid increase of farmland development (konden) by millionaires and dominant temples and shrines that became active due to enforcement of Konden Einen Shizai Law (the Law permitting permanent ownership of newly cultivated land) was the origin of formation of the plan of jori.
Yoro ritsuryo code (code promulgated in the Yoro period) describes 'when alloting farmland is finished, record its cho and dan and shishi (The northern, southern, eastern, and western boundaries).'
In other words, only area and borders of alloted farmland were recorded, but neither jori naming system to specify its absolute position nor chiwari according to jori were stipulated.
As new rice fields increase, work to decide land owners and borders exploded. Therefore, handen shuju under the farmland inspection and allotment law significantly delayed. It is thought that a unified methodology to specify land was required to ease the work, so jori naming system was introduced.
As jori naming system was established, influencial people started to develop new rice fields according to jori so that they could claim their land ownership easier. Many jori chiwari throughout Japan are thought to be done together with this development of new rice fields.
However, origin of some jori remains are thought to date back before establishment of jori naming system. In addition, remains of regularly divided chiwari that do not fit in one-cho square are confirmed, so there still is room to study about the origin of jori chiwari.
The plan of jori that was created due to needs of inspection and allotment of rice fields and management of newly developed rice fields was continuously used after the 10th centry, when handen shuju was not enforced any more. This is because kokushi (provincial governors) and kokuga (provincial government offices) utilized the jori naming method and handen map as the framework for land management and judgement of rights and obligations. In addition, it is confirmed that there existed plan of jori in shoen (manor in medieval Japan) with Funyu no ken (the right to keep the tax agents from entering the property) after the 12th century that is concluded within shoen, which indicates that the plan was actively utilized both by public and private organizations.
Jori chiwari remained in many places. As long as manual cultivation remained, there was no need to reorganize existing chiwari. However, when new rice fields were developed, chiwari that is not based on jori became common because the jori naming method was not binding any more.
After the Meiji period, revision of rice fields were done in various regions, and enactment of The Readjustment of Arable Land Act in 1889 accelerated it. Business purposes were mainly land readjustment and improvement of irrigation channels and drainage, but in west Japan where regular sections by jori were pervasive, land readjustment was not required and enforcement was limited in some lands with poor drainage. In east Japan, on the other hand, many jori chiwari had been lost or deformed due to floods. Therefore, readjustment of agricultural lands performed as cultivation and improvement of drainage together with improvement of rivers were done independantly from jori.
In agricultural field improvement project that was started in the 1960s, farm lands were re-divided using 30 are (30m x 100m) as a unit, so many remains of jori were lost.
Remains of chiwari based on the plan of jori are called jori remains.
Some jori remains are maintained as agricultural lands virtually unchanged even now, while others are buried underground.
How to find jori remains
To confirm buried jori remains, excavation is required, but it is possible for people other than specialists to find other jori remains. There are people who research jori remains as a hobby out of interest in history and geography. In addition, jori remains are effective as materials for study and research by students.
Basically, use large scale maps such as 1/25,000 scale maps issued by Geographical Survey Institute. On transparent paper etc., draw grid lines with intervals equivalent to 109 meters according to the scale of the map, and put it on the map. If streets, ditches, or paths between rice fields align with the grid lines to some extent, it is highly probable to be jori remains. However, if the streets and ditches are perfect straight lines, they are rather considered to be recent allocation.
Geographical names such as 'Shichijo,' 'Juri,' and 'Ichi no Tsubo' often stem from the jori naming system and give clue to restore jori arragement.