<論説>「藤原京の成立」遺構解釈の一例 (特集 : 都市)

Abstract

奈良文化財研究所、奈良県立橿原考古学研究所、橿原市教育委員会、桜井市教育委員会、明日香村教育委員会は、宮を含め藤原京で発掘調査をおこなっている。発掘調査によって、宮や京のより確かな姿が明らかになってきた。本稿では、最近の発掘調査成果を紹介し、藤原京に関する遺構解釈の一例を提示した。解釈の方針は、発掘調査成果を文献記録に対照させてもし整合すれば、その対応関係を認めるというものである。藤原宮・京ではこれまでに二時期の条坊遺構が発見されている。第一次条坊は宮東北部にとどまっており、第二次条坊は宮・京全域におよんでいる。宮造営のために掘られた運河から出土した遺物をめぐる研究を紹介し、これらの成果を合わせて、第一次条坊は『日本書紀』天武五年目記録する造都の企画とその中断の記事に、第二次条坊は天武十一年に開始した造都に、それぞれ対応するとする考えを支持した。さらに藤原京で条坊施工が迅速に進んだ理由を、既存の水田域を活用したことにあったと推定した。

The archaeological site of the Fujiwara Capital has long been investigated by several organizations including the Nara National Research Institute for Cultural Properties, the Archaeological Institute of Kashihara, Nara Prefecture, the Educational Board of Kashihara City, the Educational Board of Sakurai City, and the Educational Board of Asuka Village. The archaeological investigations have uncovered new details about the ancient city and palace. This paper provides the latest findings from recent archaeological research and an archaeological analysis to help understanding the building process of the Fujiwara Capital and its palace. In this study, I examined not only archaeological data but also associated historical materials, and accepted evidence that proved consistent with either interpretation. Archaeological investigations have revealed that there were features that indicate the existence of a city grid from two different periods in the sites of the Fujiwara Capital and palace. The features of an earlier city grid disappear at the area in the northwest part of the palace site, whereas the features of a later city grid extend over all parts of the palace and capital site. Additionally, I examined artifacts recovered from the remains of a canal that had been dug for construction of the palace. The study provides further evidence of a theory that the earlier city grid is associated with the historical event of planning and halt of the capital construction in Tenmu 5 (AD 676) described in Nihon Shoki (Chronicles of Japan), and the later city grid is associated with the historical event of restarting the capital construction in Tenmu 11(AD 682). Archaeological excavations revealed that the layout of the city and the palace was planned and constructed as a unit in the context of the later city grid. The center of the capital was positioned at the intersection of Suzaku Oji (the central avenue) and Gojo Oji (fifth street). The excavation conducted at the location of the center of the capital was carried out during the 148th investigation, and it revealed that the position of the center approximately corresponded to the middle of the South Gate of the Imperial Audience Hall Compound. The South Gate was a pivotal building of the palace, positioned approximately 80 meters south of the Imperial Audience Hall, and located at the junction of the Imperial Audience Hall Compound and the State Halls Compound. The palace area was in a rectangle surrounded by the Great Walls measuring 907 meters in the north-south direction and 925 meters in the east-west direction. The outer gates were positioned leading to the streets and avenues, kanji and oji. Moats were excavated outside the Great Wall. The palace area was surrounded by vacant spaces 70 to 80 meters in width, positioned outside the moats. The streets and avenues were set adjacent to the vacant spaces. The streets and avenues or oji (wide arteries) were set at intervals of 1 ri (equal to 530 meters). The roads of kanji (middle ways) were set in the middle (running parallel and in the midst of each pair) of oji, and the roads of koji (narrow lanes) were set in the middle of oji and kanji. These wide, middle and narrow streets and avenues formed a city grid in the shape of a square measuring 10 ri (equal to 5.3 kilometers) on a side. Some roads were connected to existing ancient roads outside of the capital, such as the Sanjo Oji (third avenue) leading to Yoko Oji, the Higashi Nibo Oji (eastern second avenue) leading to Nakatsu-michi, and Nishi Nibo Oji (western second avenue) leading to Shimotsu-michi. The Fujiwara Capital was a geometrically designed artificial city in which the palace was positioned at the center from which the city area stretched outward in concentric square pattern. Emperor Jito moved the imperial residence from the Asuka Kiyomihara Palace to the Fujiwara Palace on the 6th day of the twelfth month the year corresponding to 694. This was a revolutionary event in the urban history of Japan, since the Fujiwara Capital was the first example of a planned city involving an imperial palace. The emergence of the Fujiwara Capital changed the traditional setting of palace and city, and served as a model for subsequent capitals in this country. Furthermore, this study suggests that the construction of this unprecedented capital and the setting of the city grid were achieved rapidly in order to make use of the grid that had been used for paddy fields.