Sankakubuchi Shinjukyo Mirror (三角縁神獣鏡)

Sankakubuchi Shinjukyo Mirror/Sankakuen Shinjukyo Mirror is a kind of bronze mirror and large mirror engraving divine beasts with a triangular-rim in its cross-section.

Summary

Many were discovered in tumulus during the early Japanese Kofun period (tumulus period) and more than 400 have already been detected. The diameter is about twenty centimeters on average. The divine beasts (image of a deity and holy animals) were cast on the back and many mirrors included the names of eras of China and the Wei dynasty (Three States Period) in inscriptions.

As for the reason for the triangular-rim, there are some theories that most of mirrors were convex and it was structurally easier to make them with a triangular-rim, or that wooden fences surrounding a holy place were the model. In China, they were discovered only near Shaoxing in the second to third century.

Before the third century when the Sankakubuchi Shinjukyo Mirror appeared, about sixty Chinese mirrors called Gabuntai Shinjukyo Mirrors (Mirror with figures of deities and sacred animals) in a kind of 'mirror with engravings of divine beasts.'
The center of their distribution was Kinai region (the five capital provinces surrounding the ancient capitals of Nara and Kyoto), not the northern part of Kyushu region. The image of the Sankakubuchi Shinjukyo Mirror was created by artfully changing the image of the Gabuntai Shinjukyo Mirror.

Recent study

Recent studies show that the cross-section surface of the mirror changed with the times. Though older mirrors had thick outer edges and thin inner edges, the outer edge became thinner while there was no change in the inner edge over time and finally they became the same thickness. The chronology of the five-phase type in view of these changes, patterns and arrangements was completed. As the first phase can be guessed to be around 239 or 240, based on about more than ten years per phase, the second phase is considered to be around 250, the third to be around 260 and the same for later phases.

By utilizing this chronology in the type, the phase of the mirror discovered in the tumulus made it possible to judge if the tumulus is chronologically old. However, the place of production has been a tough discussion.

A recent study by Shinya FUKUNAGA of Osaka University in observing bodkins of more than a thousand of mirrors including 350 of Sankakubuchi Shinjukyo Mirror showed that the shape of the bodkin of Sankakubuchi Shinjukyo Mirror was square and different from that of other mirrors which were round or semicircle. Besides, a group of Chinese craftsmen that made bodkins of the mirrors in a square shape made the Sankakubuchi Shinjukyo Mirror and their skills could lead to government-operated crafts in the Wei dynasty. New theory that it was Sankakubuchi Shinjukyo Mirror that Wei dynasty specially casted for presenting as an imperial grant to Himiko and Iyo has been submitted.

The theory of Himiko's mirror

Based on the story that the princess of Yamatai-Koku kingdom, Himiko was considered to be dispatched to the Wei dynasty and according to a description in the Chinese history book "Sangokushi" (Three Kingdom Saga - history book) 'Gishiwajinden' (literally, an 'Account of the Wa' in "The History of the Wei Dynasty") that in 239 the Emperor of the Wei dynasty (Three Kingdoms) gave a hundred bronze mirrors as an imperial grant to Himiko, there is the theory that Sankakubuchi Shinjukyo Mirror was the said mirror and it was produced in the Wei dynasty or Rakuro County or Taiho County (ancient counties that existed in the northern Korean Peninsula) in the Korean Peninsula.

When Shinjukyo (the mirror engraved divine beasts) was discovered in the Tsubaiotsukayama-kofun Tumulus in Yamashiro-cho, Kyoto Prefecture (Kyoto Prefecture) (currently, Kizugawa City) in 1953, Yukio KOBAYASHI focused on the fact that the same form of mirrors were discovered in the various places in Japan and advocated Yamatai-Koku kingdom located in Yamato and the process of the establishment of an ancient government that Shinjukyo granted to Himiko by later Yamato sovereignty (the ancient Japan sovereignty) were given to Gozoku (local ruling family) in the various places. However, some people say that it is impossible to imagine such a dynamic process with the distributing the same form of mirrors. Recently, the case of many Sankakubuchi Shinjukyo Mirrors buried with a dead person in the Kurozuka Tumulus in Nara Prefecture was clarified, which reflected that the Sankakubuchi Shinjukyo Mirror was not so uncommon amongst buried people.

The theory of mirrors being made in Japan

On the other hand, because of the fact that no mirror similar to the Sankakubuchi Shinjukyo Mirror was ever discovered in China and that some mirrors had the name of eras already changed in China or had nonexistent eras, there are theories that they were made in Japan or produced by the craftsmen that came from China, or they were made in China and loaded on a ship destined to Japan or they were modeled on Chinese mirrors and produced in Japan.

Discussion about the Sankakubuchi Shinjukyo Mirror

Because Sankakubuchi Shinjukyo Mirrors were discovered mainly in the Kinai region, many researchers advocating the Yamatai-Koku kingdom in the Kinai region maintain Himiko's mirror and many researchers advocating Yamatai-Koku kingdom in Kyushu region maintain the mirrors were produced in Japan. However, some researchers maintaining that the mirrors were produced in Japan advocate Yamatai-Koku kingdom being in the Kinai region. Some of them advocate that the Sankakubuchi Shinjukyo Mirror was produced in Japan by craftsmen and others in the Wu dynasty (Three Kingdom) in celebration of Himiko's dispatch.
On the other hand, researchers advocating the Yamatai-Koku kingdom in the Kyushu region consider the all Sankakubuchi Shinjukyo Mirrors were be forged by future generations (though the name of era in Wei dynasty was inscribed on them.)
Researchers advocating that the mirror was produced in Japan point out the following questions while those advocating Himiko's mirror disagree.

Questions
It doesn't chronologically match because Sankakubuchi Shinjukyo Mirror was discovered only in a tumulus after the fourth century, never in tombs after the third century which corresponds to the era of the Yamatai-Koku kingdom.

No Sankakubuchi Shinjukyo Mirrors have been discovered in China and Chinese scholars say that it is not Chinese.

There is the mirror with the inscription of the name of a Chinese era which didn't exist after the change of the era.

Though 100 bronze mirrors were given to Himiko as an imperial grant, many more Sankakubuchi Shinjukyo Mirrors were discovered.

Counterargument
No Sankakubuchi Shinjukyo Mirrors were left in China because it was specially made for theYamatai-Koku kingdom.

The third year of Keisho (239) was the year when the month of the New Year of the fourth year of Keisho was regarded as being after December, which showed it was a time of turmoil.

Later, as well, Himiko was given bronze mirrors several times.

Against the argument that Sankakubuchi Shinjukyo Mirror was discovered only in tumulus after the fourth century, it consistently shows that this mirror was made in the Wei dynasty because the beginning of the Tumulus period was moved up to the third century and it was discovered in the tumulus chronologically in the third century due to the recent study results of the chronology in annual rings. That mirrors inscribed with 239 and 240 were also made in those years is understandable without question. On the contrary, the theory that this mirror was not related to the Yamatai-Koku kingdom despite the name of the era as maintained by researchers who advocate Yamatai-Koku kingdom in Kyushu region is rather inconsistent.

Though there is no crucial evidence to determine whether the Sankakubuchi Shinjukyo Mirror was made in the Wei dynasty or in Japan, it is one of the compelling evidences of the Yamato theory of the Yamatai-Koku kingdom because the mirror inscribed with the years 239 and 240 can be considered to be mirrors from the third century as seen when counting years according to the accepted view of chronology in recent years. There is little doubt that the person who made the mirror wanted to use the name of Wei for some reason.

Sankakubuchi Shinjukyo Mirror inscribed with counted years

The Sankakubuchi Shinjukyo Mirror has tetrahedral mirrors with the counted years inscribed. There are three mirrors, 'Keisho sannen' (the third year of Keisho) mirror discovered in Kanbara-jinja Shrine kofun Tumulus in oaza (an administrative unit) Kanbara, Kamo-cho, Unnan City, Shimane Prefecture, the same form of 'Seishi (Wei) gannen' (the first year of Seishi) mirrors discovered in Kanizawa-kofun Tumulus in Kanizawa, Shibasaki-machi, Takasaki City, Gunma Prefecture, Morio-kofun Tumulus in aza Ichio, Morio, Toyooka City, Hyogo Prefecture and in Gokaroyashiki-kofun Tumulus in Takeshima Island, Shunan City (the former, Shinnanyo City), Yamaguchi Prefecture. These mirrors have images of deities and breasts in patterns all set in the same direction.

Keisho sannen' mirror
In 239, Ching has made this mirror. Here is my history. I used to live in Yangzhou of Wu in China as a mirror maker but now I am in exile living in the end of the land. (After this sentence it is hard to comprehend because of the partly corrupted characters) May your life be long like a golden stone and may your flesh and blood be prosperous.''
Seishi gannen' mirror
In 240, Ching has made this mirror. Here is my history. I used to live in Yangzhou of Wu in China as a mirror maker but now I am in exile living in the end of the land. May your life be long like a golden stone and may your flesh and blood be prosperous.'

Tumulus where the Sankakubuchi Shinjukyo Mirror was discovered

Aizu-Otsukayama-kofun Tumulus (Aizuwakamatsu City, Fukushima Prefecture, one of the oldest tumulus in the Tohoku region)
Shido-Otsukayama-kofun Tumulus (Nishi-shindo, Hiratsuka City, Kanagawa Prefecture)
Morishogunzuka-kofun Tumulus (Chikuma City, Nagano Prefecture, the inscription of 'Tennohitsuki,' a large keyhole-shaped tomb mound, 100 meters long of the hill tomb)
Kai-Choshizuka-kofun Tumulus (Kofu City, Yamanashi Prefecture (the former, Nakamichi-machi, Higashiyatsushiro County), a large keyhole-shaped tomb mound)
Ichirinyama-kofun Tumulus (Unumanishi-machi, Kagamihara City, Gifu Prefecture, a round barrow)
Yukinoyama-kofun Tumulus (Higashiomi City, Shiga Prefecture, a large keyhole-shaped tomb mound)
Akamonue-kofun Tumulus (Hamamatsu City, Shizuoka Prefecture, a large keyhole-shaped tomb mound)
Tsubaiotsukayama-kofun Tumulus (Kizugawa City, Kyoto Prefecture, a large keyhole-shaped tomb mound in the early period, a plectrum form in the front part)
Nishimotomezuka-kofun Tumulus (Nada Ward, Kobe City, Hyogo Prefecture, zenpo-koho (square front, square back mound)
Kurozuka-kofun Tumulus (Tenri City, Nara Prefecture, a large keyhole-shaped tomb mound)
Sakurai Chausuyama-kofun Tumulus (Sakurai City, Nara Prefecture, a large keyhole-shaped tomb mound in the early period, a handled-mirror form in the front part)
Bizen Kurumazuka-kofun Tumulus (Okayama City, Okayama Prefecture)
Shirotori-kofun Tumulus (Takaya-cho, Higashihiroshima City, Hiroshima Prefecture)
Nakahachiman-kofun Tumulus (Hakata Ward, Fukuoka City, Sankakubuchi Goshin Shijukyo, in the early period, not a precisely round shape in the rounded part, about seventy-five meters long in the hill tomb)

The discovery of Sankakubuchi Shinjukyo Mirrors by prefecture amount to more than fifty in Kyoto Prefecture and fourty-four in Nara Prefecture, which are outstanding, followed by thirty or more in Fukuoka and Osaka Prefectures. This shows that many Sankakubuchi Shinjukyo Mirrors were discovered in the Kinki region (Nara, Osaka, and Kyoto Prefectures) centering on Nara Prefecture. Besides, more than 170 were discovered in the Kinki region, accounting for more than half of the total.