トピックス Topics

藤原宮朝堂院における儀式遺構の発見

Discovery of Ritual Features in theState Halls Compound, Fujiwara
Palace2016 年度は、藤原宮の発掘調査（飛鳥藤原第 189 次）で大きな発見がありました。みつかったのは幢幡（どうばん）遺構、場所は大極殿院南門のすぐ南、朝堂院の北端部です。
『続日本紀』には大宝元年（701）の元日朝賀において、７本の幢幡（烏形幢、日・月、青龍・朱雀・白虎・玄武の四神幡）を「正門」（大極殿院南門）に立てたとあります。
今回発見した幢幡遺構は、この７本の幢幡を立てた遺構と考えられます。この元日朝賀の様子は、「文物の儀、是に備れり。」と語られ、律令国家完成の宣言と一般に理解されています。この発見は大きなニュースになりました。
この幢幡遺構は、藤原宮中軸上に１基、その東西にそれぞれ３基が三角形状をなすように、合計７基の大型柱穴を配置するものです。幢幡遺構を『続日本紀』の記述から復元すれば、中央に烏形幢、その東に日像、西に月像、東北に青龍幡、南東に朱雀幡、西北に玄武幡、西南に白虎幡となります。
中央の柱穴と東の３基の柱穴は、2008 年度の第 153 次調査ですでにみつけていました。藤原宮中軸で折り返すと７基となることから、当時も７本の幢幡に関わる遺構の可能性を考えましたが、確証を得るまでにはいたりませんでした。平城宮第二次大極殿でみられるように、藤原宮大極殿の前にも７基の柱穴が一直線に並ぶ可能性が、大極殿院内庭が未調査であったため、残されていたからです。
その後、2014 年度・2015 年度に大極殿院内庭の調査をおこないましたが、大極殿の前面には幢幡に関わる遺構はありませんでした。2008 年度の第 153 次調査でみつけていた柱穴が再び幢幡遺構の候補として浮上することになったのです。
そこで、2016 年度の第 189 次調査では、第 153 次調査区のすぐ西側に調査区を設け、第 153 次調査でみつけていた柱穴の西側の対称位置にも、同様の柱穴が存在するのかを確かめる調査をおこないました。その結果、予想通り東側と対称の位置に３基の大型柱穴を発見しました。これにより、ついに７基の大型柱穴からなる幢幡遺構の全容があきらかになったのです。
藤原宮朝堂院と大極殿院の継続的な発掘調査が、８年越しに７本の幢幡の姿をあきらかにしたのです。

The 2016 fiscal year saw a tremendous discovery in an excavation at
the Fujiwara palace (Asuka/Fujiwara No. 189). It was the discovery of afeature related to ritual banners, at a location just south of the southerngate of the Imperial Audience Hall Compound, at the northern edge of
the State Halls Compound.
The Shoku Nihongi chronicle records that for the ceremonial NewYear’s greetings to the emperor in the first year of the Taihō era (701),
seven banners (representing a crow, the sun and moon, and the four
directional deities: Seiryū, Suzaku, Byakko, and Genbu) were erected
at the “main gate” (the Imperial Audience Hall Compound’s southerngate). The recently discovered banner feature is thought to have been forthe purpose of erecting these seven banners. The New Year’s greetings
ceremony is described as showing that “the rites of civilization are nowcomplete,” which is broadly understood as a declaration of the completion of the ritsuryō state. The discovery became a major news story.
This banner feature has a total of seven large post holes arranged
with one lying on the central axis of the Fujiwara palace, and the others forming triangular shapes to its east and west. Reconstructing thefeature based on the Shoku Nihongi description, the crow banner would
be placed in the center, with the sun to its east and moon to its west,
then Seiryū and Suzaku to the northeast and southeast, and Genbu andByakko to the northwest and southwest.
The central post hole and the three to the east had previously been
discovered in excavation No. 153 during the 2008 fiscal year. While thepossibility of a relationship with the ritual banners was considered at thetime, as symmetrical placement would result in seven items, it could
not then be confirmed. The possibility remained that seven banners had
been placed in a straight line in the manner seen in the Latter Imperial
Audience Hall Compound of the Nara palace, as the inner court of theFujiwara Imperial Audience Hall Compound had yet to be investigated.
Subsequently, excavations were conducted in the Imperial Audience
Hall Compound’s inner court in the 2014 and 2015 fiscal years, with nofeatures related to banners being found in front of the Imperial AudienceHall. Thus the post holes discovered in excavation No. 153 of fiscal 2008
once again arose as candidates for the banner feature.
Then, in investigation No. 189 of the 2016 fiscal year, an excavation
precinct was set up just west of that of excavation No. 153, and investigation was undertaken to confirm whether similar post holes existed atlocations symmetrically opposite those discovered in the previous excavation. As a result, three large post holes were discovered as expected insymmetrical fashion to those on the eastern side. With this, the bannerfeature comprised of seven large post holes came to light.
With the continual excavations at the Fujiwara palace State Halls andImperial Audience Hall Compounds, the shape of all seven banners wasclarified over an eight-year period.

第 189 次調査区全景（南から）Panoramic view of the investigated area of excavation No. 189 (fromthe south)28幢幡遺構と復元した幢幡（南から）Banner features with replicated banners (from the south)