Masuda no Iwafune: An Asuka-Period Stone Monument in Japan
Site at a Glance
- Rating
- 4.5
- Popularity
- Low
- Country
- Japan
- Primary era
- Medieval
- External website
- Open
- Eras represented
- Medieval
- Civilizations
- Yamato
- Site type
- Burial
- Remains
- Tomb
On this page11 sections
History
Masuda no Iwafune is a massive Asuka-period stone monument in Kashihara, Japan, generally dated to the seventh century. It belongs to the group of distinctive carved stone structures associated with Asuka, a region of the Nara area and a period of major political and religious change in central Japan. Often described as the largest of the Asuka stone structures, it has been regarded as a sightseeing place since the Edo period.
Origins and proposed functions
The monument’s date is usually placed in the seventh century because its working methods and the dimensions of its cavities resemble features of the very late Kofun period. The Kofun period was known for large burial mounds and carefully developed stone burial chambers. Masuda no Iwafune’s exact purpose has remained uncertain, and several interpretations have developed around its form.
An early tradition identifies it as the base of a stone stele praising the construction of Masuda Pond in 822. According to this tradition, Kōbō Daishi, the posthumous title of the Buddhist monk Kūkai and founder of the Shingon school, wrote the inscription. The monument’s name is linked to this association. The stele was later said to have been broken up for building material in the walls of Takatori Castle, leaving the base in place.
Other interpretations have treated the structure as an astronomical observation platform, perhaps with pillars placed in its two cavities and a crossbeam set above them. It has also been proposed as a cremation tomb, in which remains were placed in the cavities and covered with stone lids, or as a lookout platform.
A possible unfinished burial chamber
The interpretation now given greatest weight regards Masuda no Iwafune as an intended horizontal-entry stone burial chamber. Such a chamber is entered from the side through a lateral passage rather than from above. Under this reconstruction, the monument would have been turned over, making its present north wall the underside of the chamber.
The different condition of the two cavities supports a theory of damage during construction. Water remains in the eastern cavity, while the western cavity is dry, a difference that has been taken to indicate a crack in the western cavity. The work may consequently have been abandoned after the damage was discovered.
Archaeologist Kanekatsu Inokuma argued that Masuda no Iwafune and the Stone Hoden at Takasago in Hyogo Prefecture were two unsuccessful attempts to create chambers from hard quartz diorite. In this interpretation, builders eventually completed a nearby chamber for Kengoshizuka Kofun, about 500 metres southeast of Masuda no Iwafune, by using softer Tatsuyama stone from the Takasago area.
Heritage status
Nara Prefecture designates the monument as a historic site under the name Iwafune. On 24 April 2015, it also became a component cultural property of Japan Heritage under the registered name Iwafune.
Remains
Masuda no Iwafune stands near the summit of Iwafune-yama, on a hillside west of Shirokashi Minami Elementary School in Kashihara New Town. It is a roughly trapezoidal block of hard quartz diorite, with almost vertical eastern and western sides. The stone measures about 11 metres from east to west, 8 metres from north to south, and 4.7 metres in height on its north side. Estimates of its weight range from approximately 160 tonnes to 500 or 600 tonnes. It is now generally considered to have remained in its present position from the beginning.
Upper groove and cavities
Central groove
A groove about 1.6 metres wide runs east to west across the upper surface and descends toward the sides. Two square cavities, each around 1.6 metres wide and 1.3 metres deep, were cut into this groove. They are separated by an interval of roughly 1.4 metres. The eastern cavity holds water, whereas the western cavity is dry, a physical difference that forms part of the proposed reconstruction of the monument as a damaged burial chamber.
Possible chamber structure
The arrangement of the groove and cavities has also allowed other reconstructions. In the astronomical-platform interpretation, the cavities would have held stone pillars supporting a crossbeam. In the cremation-tomb interpretation, they would have received cremated remains and been sealed with stone lids. These proposed functions reflect the monument’s unusual arrangement and its unfinished state.
Unfinished stone surfaces
Lower grooves
The lower part of the block contains a grid of grooves approximately 10 centimetres deep. These marks are understood as part of an incomplete effort to flatten the surface. Their presence indicates that the stone was being shaped rather than simply used in its natural form.
North wall
The present north wall carries 30 vertical and 7 horizontal grooves arranged in a grid extending from one edge. The lines are fairly uniform but crudely worked. Together with the lower grooves, they show that shaping and finishing stopped before the intended form was complete.
