Abstract
On this paper, part4, we have investigated the sites of Dairi, Chugu, Saigu and Yobaigu, which were the residence of the Emperor or the Empress in Heijo-kyu, as well as the characters of the supreme halls of such residences described in the Shoku-nihongi. The main results obtained from the above study are as follows : 1) Dairi, or the Imperial Domicile, of Heijo-kyu was erected to the east of the original Daigoku-den. It is supposed that the supreme hall of Dairi was Naian-den described in the Shoku-nihongi, and the quarter with the Daian-den in the center existed to the south of Dairi before the transfer of the capital to Kuni-kyo. 2) It is probably possible that Chugu was the identical palace with the principal palace (sei-miya, 正宮, or kinsho, 禁省) of Heijo-kyu where Dairi existed, and the supreme hall of Chugu was the Daian-den. 3) Before the transfer of the capital to Kuni-kyo (724〜740A. D.), the supreme hall of Chugu at the Heijo-kyu was used as the main building for the ceremonies and the banquets in Nai-cho, or the private precincts of the Imperial Palace. On the contrary, after the return of the Government to Heijo-kyo (745A. D.), the supreme hall of Dairi took the place of that of Chugu as the main building in Nai-cho. It may have mainly resulted in the following facts : when the capital was transfered to Kuni-kyo, the Daigoku-den of Heijo Imperial palace was moved and rebuild in Kuni Imperial Palace, and that, after the capital was transferred again to Heijo-kyo, Daigoku-den was not reconstructed in the former place and the Daian-den existed in the southern precinct of Dairi was used as Daigoku-den. 4) Saigu-zenden (西宮前殿) described in the chapter of the Empress Shotoku of the Shoku-nihongi is supposed to have been the supreme hall in that palace which was constructed around the first year of the Tempyo-Hoji (天平宝字) period (757A. D.) at the former site of the original Daigoku-den erected to the north of the Suzakumon (朱雀門). Saigu-zenden was used for the Gensho-Choga (元正朝賀, the national ceremony in which Emperor received New Year's congratulations from the whole body of officials) and the formal banquet of the Niiname-sai (新嘗祭, the Harvest Festival) in the Imperial palace. Judging from this fact, Saigu-zenden is considered to have been the main building as the State Chamber in Heijo-kyu, next in importance to the Daigoku-den. 5) Zen-den (前殿) recorded in the chapter of the Emperor Konin of the Shoku-nihongi is supposed not to have been the supreme hall of Dairi, but used as the supreme hall of Yobaigu, the residence of the Emperor Konin.
