Tombs that gave a period its name
“Kofun” simply means “old tomb” in Japanese, and the term has given its name to the period from roughly the middle of the third century CE to the late sixth or early seventh century, with the age of tomb-building fading out over the following decades. During these centuries, thousands of burial mounds were built across the islands from Kyushu to the northeast. Most are small, but the largest rank among the biggest burial monuments anywhere, and they offer a rare look at the politics of a society that left almost no writing of its own.
The keyhole shape
The signature form is the zenpo-koen-fun, or keyhole-shaped mound, which joins a round or square rear part to a trapezoidal front. Other tombs are simply round, square or, more rarely, scallop-shaped. Keyhole mounds were generally the preserve of the highest elites, and the biggest are found in the Kinai region around present-day Nara and Osaka, the heartland of the Yamato rulers.
Construction used earth built up in tiers, with the slopes often covered in river stones, a technique called fukiishi, so that the mound would have gleamed. Many are surrounded by one or more moats. The standard view is that the size and shape of a tomb expressed rank within the Yamato political order, and that the spread of the keyhole design across regions reflects ties between the central rulers and local leaders, though the details of that relationship are debated.
The largest tombs
The largest is the Daisen Kofun, in Sakai, Osaka, traditionally associated with the emperor Nintoku and dated to the fifth century. It is about 480 metres long and surrounded by triple moats, and it is often compared with the Giza pyramid complex and the Khufu Great Pyramid as one of the world’s largest funerary monuments, depending on whether one measures volume, height or footprint. The Daisen and other tombs of the Mozu and Furuichi groups were inscribed on the UNESCO World Heritage list in 2019.
Construction on this scale needed substantial organised labour, plus surveying and planning, though we know little about how workers were recruited. Nothing suggests the builders used the monumental stone architecture seen in Egypt. They moved earth and shaped it, and their innovations lay in layout and scale.
Haniwa
Mounds were decorated with haniwa, hollow clay objects set in rows on the terraces and around the edges. Early haniwa were plain cylinders, perhaps marking off the sacred space. Later ones took the form of houses, boats, shields, birds and animals such as horses, as well as people: warriors, farmers, musicians, women with offering vessels and priestly figures. They give excellent information on clothing, armour and daily objects, and the clay horses with saddles and bridles show the growing role of cavalry.
Their purpose is still discussed. Some believe they defined a ritual space; others think the scenes represented a funeral procession or the world of the dead. The Nihon Shoki offers a legendary explanation in which an official proposed replacing the burial of retainers alongside a ruler with clay figures. This is a story recorded centuries later and should not be treated as an eyewitness account of the origin of haniwa. Craftsmanship was high in some workshops, and while the style is nothing like the terracotta warrior craftsmanship of China, the idea of figures serving the dead has been compared.
What was inside
Early burial chambers were typically a vertical pit lined with stones or a clay-covered wooden coffin set in the mound. From the fifth century, ideas arriving from the Korean peninsula led to horizontal stone chambers with entrance passages, which could be reopened for further burials. Goods placed with the dead changed over time:
- Early: bronze mirrors, jasper and jade ornaments, and tools.
- Middle: iron weapons, armour and helmets, reflecting military change, as the ironworking spread brought plentiful iron into elite hands.
- Late: horse gear, gilt-bronze ornaments, crowns and fine ceramics, many of them in styles linked to the Korean states.
A few late tombs, such as Takamatsuzuka and Kitora in Nara Prefecture, have painted walls in a style related to continental art, and they date from the end of the tradition, around the seventh century or early eighth.
Rulers, migrants and politics
Many tombs have been connected, at least by tradition, with the early emperors and with powerful clans. The Imperial Household Agency, which manages the largest mounds as imperial tombs, usually does not allow excavation, so most evidence comes from survey, smaller tombs and surface finds. Techniques like LiDAR survey have helped to map the mounds without disturbing them. This restriction is one reason why the dating and identification of the great tombs remain uncertain, much like the way an unexcavated imperial mausoleum in China limits what can be said about its interior.
Migrants from the Korean peninsula brought knowledge of ironworking, horse riding, new ceramics and kiln technology during this period. The mounds are therefore evidence of a society closely connected with the wider region and not isolated.
The end of the tomb age
Large mounds gradually disappeared in the seventh century. The adoption of Buddhism, new burial practices including cremation, and reforms of the central government that placed limits on tomb size all contributed. The Kofun period gave way to the Asuka period, with state institutions modelled in part on the Chinese pattern and, a little later, the first written histories of Japan. The mounds that remain still dominate many landscapes, and hundreds of them are protected today.