A pyramid has been uncovered by archaeologists at Asuka, Nara, NHK World news announced his evening.
Pyramids, though not unknown in Japan, are very rare. The Zuto and Doto pagoda pyramids also in Nara are from the 8th century, but this newly discovered pyramid, is believed to be from the latter part of the 6th century (and contemporaneous with the reign of Prince Shotoku).
The Ishibutai tomb thought to be the tomb of the Soga no Umako, a powerful minister of the imperial court and leader of the ruling clan of the Yamato state. Miyako-zuka is believed to pre-date the Ishibutai tomb.
Experts believe the pyramid likely belonged to the father of Soga no Umako. Soga no Iname (蘇我 稲目, 506 – March 22, 570). Soga no Iname was a leader of the Soga clan and a statesman during the reign of Emperor Kimmei in the Asuka period. He was the first person to hold the position of Ōomi that can be verified with reasonable accuracy, in 536 AD.
Pyramids, the closest ones in proximity to Japan’s, are found in Jilin (modern-day China) which belonged to the Korean Kingdom of Koguryo (in yellow above)
According to the experts, based on a reading of the text of the ancient Nihon Shoki (see photos above) Soga no Iname is the most likely candidate for the occupant of the pyramid tomb, and because his two wives are known to have been from the Koguryo Kingdom, this provides a strong reason why the pyramidal tomb design of Koguryo would have been introduced at this time.
Update from Jiji Press via The Yomiuri Shimbun, 15th Aug, 2014
NARA (Jiji Press)—A large ancient rectangular tomb in the village of Asuka in Nara Prefecture may have had a rare pyramid shape, according to a group of archeologists.
The Miyakozuka tomb is believed to have been built in the latter half of the sixth century.
It was likely a step pyramid made of multiple stone layers, experts at the municipal education board and Kansai University’s Archaeological Research Institute said Wednesday.
The tomb may have been influenced by ancient tumuli built near the border between China and North Korea given its similar structure, according to the experts.
It is thought that Soga no Iname, a Yamato Dynasty leader who died in 570, was buried in the tomb. He is known to have had close links with people from China and the Korean Peninsula who immigrated to Japan.
After excavating the mound and surrounding areas of the Miyakozuka tomb, the group of archeologists found stair-like architectural remains at three locations.
Four layers of stones were found at one location, and one layer was discovered at each of the two other locations.
Based on the findings, the group said it believes the tomb had a pyramid-like structure with seven or eight stone layers.
The mound is estimated to have been at least 4.5 meters high on the east side and 7 meters high on the west, with each side being more than 40 meters long.
Soga no Iname is known to have had strong ties to Koguryo as he is believed to have had two wives from the ancient Korean kingdom.
The village of Asuka is known for many megalithic discoveries. They include the Ishibutai tomb believed to have been built in the seventh century for Soga no Umako, son of Iname, who died in 626.
Clay pots and ironware were unearthed from the Miyakozuka tomb in a survey started in 1967 by the Kansai University research institute and others. But the size of the mound, its structure and other details remained unknown.
For further reading, see Sakai’s list of 12 pyramids