The ancient tombs built in Japan between the third and seventh centuries AD (also in the shape of a keyhole) were oriented towards the arch of the rising sun, the divinity that the emperors linked to the mythical origin of their dynasty.
This is demonstrated by the satellite images analyzed by the experts of the Politecnico di Milano in the study published in the journal Remote Sensing.
The Japanese islands are dotted with hundreds of ancient burial mounds, the largest of which are in the shape of a keyhole and are called Kofun.
The most impressive are attributed to the semi-legendary first emperors, while the smaller ones are supposed to belong to court officers and members of the royal family.
Among these, the so-called Daisen Kofun is one of the largest monuments ever built on Earth: it measures 486 meters in length and about 36 in height, and is traditionally attributed to Nintoku, the sixteenth emperor of Japan.
There are no written sources on these tombs, while excavations are rare and limited to the smaller ones, since the largest are considered the tombs of the first semi-legendary emperors and, as such, are strictly protected by law. The protection also extends to the outside: many monuments are fenced and it is not allowed to enter the perimeter, for this reason it is impossible to obtain an accurate measurement of the size or height.
To study the orientation of over one hundred Kofuns, researchers Norma Baratta, Arianna Picotti and Giulio Magli of the Milan Polytechnic used the remote sensing technique.
The data obtained indicate a strong connection of the entrance corridors of the Kofun with the arch of the sky where the Sun and the Moon are visible every day of the year and show the orientation of the huge Kofun in the shape of a keyhole with respect to the arc of the rising / shining sun.
In particular, the Daisen Kofun is oriented towards the Sun rising at the winter solstice.
The orientation of the imperial tombs towards the Sun is in full agreement with the Japanese imperial tradition: in fact, the mythical origin of the dynasty of Japanese emperors considers them as direct descendants of the Sun goddess Amaterasu.