Jyobo system

In ancient times, during the Ritsuryo period, the capital city plan was composed of square grid streets. Its origins lie in China, but in Japan it was adopted in the Taika Reforms Imperial Edict (646) which stated, "At first, the capital city was to be renovated," and "A chief was to be appointed for each monastery in the capital, and a magistrate was to be appointed for every four monasteries." The first capital city to have a confirmed grid-based plan was Fujiwara-kyo (694-710), which had a rectangular capital area with 12 monasteries, each about 4 cho in area, arranged north to south and 8 monasteries east to west, with the palace area located in the northern part of the center. In the next capital, Heijo-kyo (the capital was moved in 710), the area of ​​the monasteries was four times larger, with 9 jo from north to south and 8 monasteries east to west as the basic structure, and the outer capital and northern border monasteries were added to the east and north. Each monastery and 16 tsubo within the monastery were marked with a number, for example, "Sakyo Sanjo Nibo 12 tsubo." The palace grounds were in the center of the north, from which Suzaku Road stretched south, with Rajomon Gate on the southern edge. Heian-kyo (the capital was moved to in 794) also had nine streets from north to south and eight blocks from east to west, but no outer capital. Unlike Heijo-kyo, the road widths were set separately, so the area of ​​the blocks and the towns within them (corresponding to the tsubo of Heijo-kyo) was completely uniform, and the towns were further divided into 32 plots consisting of "four rows and eight gates," which became the basic unit of housing land called "ichihenushi." It is believed that Dazaifu, which was established during the Ritsuryo period, and the provincial capitals of each province were also built on a scaled-down version of the capital city plan.

[Kaneda Akihiro]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

古代、律令(りつりょう)期の方格状街路で構成された都城プラン。その源流は中国にあるが、日本では大化改新の詔(みことのり)（646）に「初メテ京師(けいし)ヲ修ム」、「京ハ坊毎(ごと)ニ長一人ヲ置キ、四坊ニ令一人ヲ置ク」として採用されたものである。条坊に基づく都城プランが確認された都城としては、藤原京（694～710）が最初であり、面積約4町の正方形の坊を南北に12、東西に8配列した長方形の京域を有し、中央部北側に宮域が存在した。次の平城京（710年遷都）では、坊の面積が4倍となり、南北9条、東西8坊を基本とし、さらに東側と北側に外京および北辺坊が加わったものであった。各坊や坊内の16の坪には数詞が付されて「左京三条二坊一二坪」というように表示された。北部中央に宮域があり、そこから南へ朱雀(すざく)路が延び、南辺に羅城門があった。平安京（794年遷都）ではやはり南北9条、東西8坊であったが外京はなかった。平城京とは異なって道路幅が別に設定されていたので、坊やその内部の町（平城京の坪にあたる）の面積は完全に均一であり、町内はさらに「四行八門」からなる32区画に区分され、「一戸主(いちへぬし)」とよばれる宅地の基本単位となった。律令期に設定された大宰府(だざいふ)や各国の国府も、都城プランを縮小した形で営まれていたと考えられている。

［金田章裕］

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