“Kibiji’s Historical Heritage” Appeal Promotion Project ～ Exploring the Intrinsic Value of Sites Such as Komorizuka Kofun and the Ruins of Bitchū Kokubun-niji Temple and Sharing Their Appeal

Okayama Prefectural Ancient Kibi Cultural Properties Center and others launched the “Kibiji Historical Heritage” Promotion Project in fiscal 2020 (Reiwa 2), and it is making steady progress.

Excavation of the Historic Site of Komorizuka Kofun has already been completed, revealing many new facts. Artifacts have also been re-examined, gradually uncovering the intrinsic value of Komorizuka Kofun.

In addition, excavation of the Historic Site of the Bitchu Kokubun-niji Temple Ruins began in fiscal 2023. Efforts to promote its appeal have also begun.

We spoke with Matsuo Yoshiko and Hirano Yuri, who are in charge of the “Kibiji Historical Heritage” Promotion Project, about the achievements of the past four years and plans for the future.

About the Okayama Prefectural Ancient Kibi Cultural Properties Center

The Okayama Prefectural Ancient Kibi Cultural Properties Center is located in Nishihanajiri, Kita Ward, Okayama City.

History

In 1981, the archaeological center concept was presented as part of the Okayama Prefecture New Comprehensive Welfare Plan.

In the basic plan of the Okayama Prefecture New Comprehensive Welfare Plan, under “Protection and Preservation of Cultural Properties,” one of the key cultural policy measures, it stated that “for buried cultural properties, a Buried Cultural Properties Research Center will be established to conduct research, preservation, and exhibition of materials.”

Three years later, in 1984, the Okayama Prefectural Ancient Kibi Cultural Properties Center opened under the Okayama Prefectural Board of Education.

As of April 2024, 37 staff members work across the General Affairs Division and Survey Divisions 1 through 3.

Activities

Its activities comprise the following four areas:

• Research: Distribution, confirmation, and excavation surveys; restoration of excavated items; publication of reports
• Preservation and storage: Collection management and conservation treatment
• Public outreach: Exhibitions, loans, publication of educational materials, and website
• Guidance and support: Survey techniques workshops and excavation guidance

Exhibitions

The Okayama Prefectural Ancient Kibi Cultural Properties Center in Nishihanajiri has an exhibition space with permanent displays.

It also holds special exhibitions twice a year, as well as occasional themed exhibitions.

Events

The Center also holds many events.

• Various courses, report sessions, and lectures: Scheduled throughout the year.
• Tsushima Site Yayoi Festival: Now an annual event.
• Summer vacation hands-on learning: Popular with children.

And the on-site briefings at active excavation sites are packed with the latest information.

Digital Library

The Center’s website “Digital Library” houses a wide range of materials, including previously published excavation reports and various pamphlets and learning resources, which can be downloaded freely.

Overview of the “Kibiji Historical Heritage” Promotion Project

Let us introduce the “Kibiji Historical Heritage” Promotion Project, which has been underway since 2020, led by the Cultural Properties Division of the Okayama Prefectural Board of Education and the Okayama Prefectural Ancient Kibi Cultural Properties Center.

Okayama Prefecture Cultural Properties Preservation and Utilization Master Plan

In November 2019, the Okayama Prefecture Cultural Properties Preservation and Utilization Master Plan was established in alignment with the direction of the New Sunny Country Okayama Lively Plan and the Okayama Cultural Promotion Vision. It includes the following statement:

Komorizuka Kofun and the Bitchu Kokubun-niji Temple Ruins are located within “Kibiji Fudoki-no-Oka” and are also at the heart of Kibiji, one of the prefecture’s leading tourist destinations. With a view to further enhancing the appeal of the entire Kibiji area, including the large kofun in the surrounding area, preservation and utilization plans will be drawn up promptly, and surveys, improvements, and utilization will be advanced in cooperation with the relevant municipalities, creating a place where visitors can experience the rich cultural heritage of “Ancient Kibi.”

Source: Okayama Prefecture Cultural Properties Preservation and Utilization Master Plan

Okayama Prefecture has 47 nationally designated historic sites.

“Among the historic sites owned by the prefecture or for which it serves as the managing body, surveys of the Kibiji historic sites had not progressed as far as those of Old Shizutani School and the Tsushima Site,” Matsuo explained.

Matsuo continued:

“First, we will spend several years conducting surveys and use the results as basic materials for future utilization. This is a medium- to long-term plan, with Komorizuka Kofun taking the lead and the Bitchu Kokubun-niji Temple Ruins following.”

The Promotion Project is an important Okayama Prefecture initiative that began in this way.

Comprehensive Survey for the Preservation and Utilization of the Historic Site of Komorizuka Kofun

Komorizuka Kofun is located in Kanbayashi, Soja City. The area encompassing the Bitchu Kokubun-ji Temple Ruins to the west and the Bitchu Kokubun-niji Temple Ruins to the east can be considered the heart of Kibiji.

Built in the 6th century, this keyhole-shaped kofun is about 100 meters long. It is also known as Kurohimezuka and has been well known since ancient times.

The horizontal stone burial chamber is open and was looted long ago. Even so, numerous valuable artifacts were unearthed in excavations inside the burial chamber conducted in 1967 and 1978.

However, the mound had never been surveyed, and research into the excavated artifacts was also insufficient.

The Promotion Project began with a comprehensive survey of Komorizuka Kofun.

A survey and mapping project was conducted in fiscal 2020, followed by excavations in fiscal 2021–2022. A Preservation and Utilization Plan was published at the end of fiscal 2020, and an Excavation Report at the end of fiscal 2022.

Comprehensive Survey for the Preservation and Utilization of the Historic Site of the Bitchu Kokubun-niji Temple Ruins and Other Sites

The Bitchu Kokubun-niji Temple was a state-sponsored temple established during the Nara period, along with Bichu Kokubun-ji Temple.

In 1971, excavations were conducted at the Bichu Kokubun-ji Temple Ruins and the Bitchu Kokubun-niji Temple Ruins. However, no surveys have ever been conducted within the temple precincts at the Bitchu Kokubun-niji Temple Ruins.

The comprehensive survey of the Bitchu Kokubun-niji Temple Ruins is scheduled to proceed from fiscal 2023 with excavations, reorganization of past survey materials, preparation of a report, and development of a preservation and utilization plan.

Progress of the Comprehensive Survey for the Preservation and Utilization of the Historic Site of Komorizuka Kofun

Here is an update on the progress of the comprehensive survey for the preservation and utilization of Komorizuka Kofun.

Kofun Survey

First, survey and excavation.

The survey used airborne laser scanning to cover an area 1.5 km east to west and 2 km north to south, including Komorizuka Kofun and the site of Bitchu Kokubun-niji Temple.

The image above is a topographic map created from the survey data, known as a red relief map. Steep slopes are shown in red and flat areas in white, making the contours of Komorizuka Kofun immediately clear.

Three-dimensional laser scanning inside the stone chamber was also carried out.

The excavation confirmed that 96 m of the mound remains. Its structure was also clarified: “two tiers, with the lower tier cut from the natural ground and the upper tier built up with earth.”

Preservation and Utilization Plan

According to the Preservation and Utilization Plan, published as scheduled, its guiding principle is “to preserve Komorizuka Kofun and, by learning about its history, foster attachment to the local area and pass on the appeal of Kibiji to future generations.”

The essential value of Komorizuka Kofun is comprehensively described as “the tomb of a great leader at the heart of Kibi who flourished in the sixth century, with a huge horizontal stone chamber and abundant grave goods in a large keyhole-shaped burial mound, and strong ties to the Yamato regime.” Its preservation was listed first among the basic policies.

Matsuo Yoshiko says:

“I don’t think historic sites and archaeological sites are things that we specialists should protect and preserve. It’s better for local people to maintain them. To do that, they need to understand their value. They need to know that these are things worth protecting. That’s why we investigate them so thoroughly and explain them.”

On-site Information Sessions

The first opportunity to share the findings of the investigation was an on-site information session at the excavation site.

One session was held in each of fiscal 2021 and fiscal 2022. There were 120 and 109 participants, respectively, and the narrow stone chamber was reportedly packed.

Lectures and Symposia

Lectures and symposia have also been held regularly.

In fiscal 2020, a three-part archaeological lecture series on Kibi was held under the title “The Era of Komorizuka Kofun.”

At the end of fiscal 2022, the final year of the investigation, the findings were presented comprehensively at the symposium “Kibi’s Last Large Keyhole-Shaped Burial Mound and Its Era.”

Use of ICT

The Preservation and Utilization Plan states: “Consideration of effective methods of communicating information using ICT (information and communications technology)”.

Here are two or three examples of new technologies besides red relief maps.
Experts examine the cross-sections of the soil layers observed in excavated trenches and draw detailed cross-sectional diagrams. In addition, this time, a cross-sectional orthographic image was created by combining multiple photographs and correcting the distortion characteristic of camera images.

This technology is much easier to view and takes the user’s perspective into account.

“The Ancient Kibi Cultural Properties Center is an educational institution, so it was wonderful to be able to collaborate with a high school.”

Matsuo Yoshiko introduced VR data of the horizontal stone chamber, created in collaboration with Okayama Prefectural Okayama Technical High School.

The images for the left and right eyes are displayed on a smartphone and viewed through a headset to create a three-dimensional effect.

ICT use is also advancing in other ways, such as publishing a 360-degree video introducing Komorizuka Kofun on YouTube.

Excavation Report

The excavation report, published at the end of fiscal 2022, is more than 200 pages long, excluding appendices.

The content is technical, but Matsuo Yoshiko offered some additional explanation.

“Artifacts discovered to date are held in various places: by the prefecture, by cities, or by individual collectors. It is extremely valuable to organize information about these artifacts and compile the results of reexamining them from the perspective of the latest observations.”

This will surely provide the information base for future use.

We asked Matsuo Yoshiko and Hirano Yuri, who are in charge of the comprehensive preservation and utilization survey of the Bitchu Kokubun-niji Temple site and other locations, which began in fiscal 2023, about its progress.

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