One way of increasing the strength and solemnity of kidan, a foundation platform found in the construction of temples, is to face it with stracked roof-tiles. This is a technique in which roof-tiles are laid flat around the foundation platform. It was popular in Paekche on the Korean Peninsula. In Japan it has emerged in temples around Otsunomiya to which the capital was moved in 667, and it may have existed in temples around Naniwanagaratoyosakimiya(652). The change was probably brought by immigration of exiled artisans after the fall of Paekche(660). However, the newly emerged kawarazumi-kidan, was a somewhat "Japanese style" kidan,different from those in Paekche. There is a possibility that the technique of kawarazumi-kidan itself was introduced about one century earlier. The Yamato Government in the 6th to 7th centuries was politically close to Paekche and learned many temple costruction techniques from Paekche, starting at the end of the 6th century, but somehow kawarazumi-kidan was not adopted. In the Asuka/Yamato region, a foundation platform with traditional stone techniques was preferred. The spread of the "Japanese style" kawarazumi-kidan around Otsunomiya and Naniwanomiya was the result of the fusion between Japanese techniques for foundation platform construction that had been accumulated since the end of 6th century, and a roof-tile stacking technique imported from Paekche. It was made possible in the new capital, which was free from Asuka traditions.

In this study, we were able to deepen knowledge by archeology and documents historical study, physics and chemistry collaborating about Green-glazed pottery and tile characterizing the Heian period.The concrete method were : arguing the researcher between pottery study and tile studies, soil analysis using the fluorescence X-rays, and analysis of the color. The most straightforward result is to have been able to clarify the actual situation of the Green-glazed pottery and tile in the kiln around Heian-kyo.In addition, we published the result of the collaboration study as a report and returned results of research to the society to hold a symposium for citizens.

Introducing a new concept of “the Buddhist capital area”, we tried to elucidate the historical characteristics of the capital area in ancient Japan by studying the social and cultural roles of Buddhist temples. “The Buddhist capital area” had three types of typical temples; (1)temples located in mountains around the capital, (2)temples linked to the powers, and (3)temples deeply involved in traffic and transportation. Through interdisciplinary research on many cases, “the Buddhist capital area” has been proven along with diversity of consisting areas. However, we could not find the same kind of “the Buddhist capital” in ancient China or Korea, which highlights the uniqueness of ancient Japanese society.