Kofun (古墳, from Sino-Japanese "ancient burial mound") are megalithic tombs or tumuli in Northeast Asia. Kofun were mainly constructed in the Japanese archipelago between the middle of the 3rd century to the early 7th century AD.^[1]

The term is the origin of the name of the Kofun period, which indicates the middle 3rd century to early–middle 6th century. Many kofun have distinctive keyhole-shaped mounds (zempō-kōen fun (前方後円墳)). The Mozu-Furuichi kofungun or tumulus clusters were inscribed on the UNESCO World Heritage List in 2019, while Ishibutai Kofun is one of a number in Asuka-Fujiwara residing on the Tentative List.^[2][3]

The kofun tumuli have assumed various shapes throughout history. The most common type of kofun is known as a zenpō-kōen-fun (前方後円墳), which is shaped like a keyhole, having one square end and one circular end, when viewed from above. There are also circular-type (empun [ja] (円墳)), "two conjoined rectangles" typed (zenpō-kōhō-fun [ja] (前方後方墳)), and square-type (hōfun [ja] (方墳)) kofun. Orientation of kofun is not specified. For example, in the Mozu kofun group, in Sakai, several of the circular parts are facing north, while other face east. However, there is no such formation in the Yanagimoto kofun group. Haniwa, terracotta figures, were arrayed above and in the surroundings to delimit and protect the sacred areas.

Kofun range from several metres to over 400 m long. The largest, which has been attributed to Emperor Nintoku, is Daisen Kofun in Sakai City, Osaka Prefecture.

The funeral chamber was located beneath the round part and comprised a group of megaliths. In 1972, the unlooted Takamatsuzuka Tomb was found in Asuka, and some details of the discovery were revealed. Inside the tightly assembled rocks, white lime plasters were pasted, and colored pictures depict the 'Asuka Beauties' of the court as well as constellations. A stone coffin was placed in the chamber, and accessories, swords, and bronze mirrors were laid both inside and outside the coffin. The wall paintings have been designated national treasures and the grave goods as important cultural property, while the tumulus is a special historic site.^[4][5]

Kofun burial mounds and their remains have been found all over Japan, including remote islands such as Nishinoshima.^[6]

A total of 161,560 kofun tomb sites have been found as of 2001. Hyōgo Prefecture has the most of all prefectures (16,577 sites), and Chiba Prefecture has the second most (13,112 sites).^[7]

Most of the tombs of chiefs in the Yayoi period were square-shaped mounds surrounded by ditches. The most notable example in the late Yayoi period is Tatetsuki Mound Tomb in Kurashiki, Okayama. The mound is about 45 metres wide and 5 metres high and has a shaft chamber. Broken pieces of Tokushu-kidai, cylindrical earthenware, were excavated around the mound.

Another prevalent type of Yayoi period tomb is the Yosumi tosshutsugata funkyūbo, a square mound with protruding corners. These tombs were built in the San'in region, a coastal area off the Sea of Japan. Unearthed articles indicate the existence of alliances between native tribes in the region.

One of the first keyhole-shaped kofun was built in the Makimuku area,^[8] the southeastern part of the Nara Basin. Hashihaka Kofun, which was built in the middle of the 3rd century AD, is 280 metres long and 30 metres high. Its scale is obviously different from previous Yayoi tombs. During the next three decades, about 10 kofun were built in the area. They are now known as the Makimuku Kofun Group. A wooden coffin was placed on the bottom of a shaft, and the surrounding walls were built up by flat stones. Finally, megalithic stones formed the roof. Bronze mirrors, iron swords, magatama, clay vessels and other artifacts were found in good condition in undisturbed tombs. Some scholars assume that the person buried in the Hashihaka kofun was the shadowy ancient Queen Himiko of Yamataikoku, mentioned in Chinese historical texts. According to these texts, Japan was called Wa, and was a confederation of numerous small tribes or countries. The construction of gigantic kofun was the result of the relatively centralized governmental structure in the Nara Basin, possibly the origin of the Yamato polity and the Imperial lineage of Japan.

During the 5th century AD, the construction of keyhole kofun began in Yamato Province; continued in Kawachi, where gigantic kofun, such as Daisen Kofun of the Emperor Nintoku, were built; and then throughout the country. The proliferation of keyhole kofun is generally assumed to be evidence of the Yamato court's expansion in this age. However, some argue that it simply shows the spread of culture based on progress in distribution, and has little to do with a political breakthrough.

A few tombs from the mid-Baekje era were excavated around the Yeongsan River basin in South Korea.^{[citation needed]} The design of these tombs are notably different. The tombs that were discovered on the Korean peninsula were built between the 5th and 6th centuries CE.^{[citation needed]} There remain questions about who were buried in these tombs such as nobility, aristocracy, warriors or mercenaries.

• Gallery
• 
  An example of keyhole-shaped mound in the Early Kofun period which was drawn in 3DCG.
  (Gosashi Kofun (Nara, Nara), 4th century)
• 
  An example of keyhole-shaped mound in the Mid-Kofun period which was drawn in 3DCG.
  (Nakatsuyama Kofun [ja] (Fujiidera, Osaka), 5th century)
• 
  An example of keyhole-shaped mound in the Late Kofun period which was drawn in 3DCG.
  (Danpusan Kofun (Nagoya), 6th century)

Keyhole-shaped kofun disappeared in the late 6th century AD, probably due to the drastic reformation in the Yamato court. Nihon Shoki records the introduction of Buddhism during this era, which led to cremation becoming the primary funerary means of the nobility.

Keyhole Kofun, or Zenpokoenfun, are a notable type of Japanese ancient tomb consisting of a square front part (前方部) and a circular back part (後円部).^[9] The part connecting the two is called the middle part (くびれ部), which looks like a keyhole when viewed from above.^[10]

Round Kofun [ja] (円墳, enpun) are a kind of kofun that possesses only a round mound and lacks the square segment.^[11]

{{Ill| Square kofun (方墳, hōfun) are a kind of kofun that possesses only a square mound and lacks the round segment. They are typically relatively smaller than the other shapes of mounded tombs.^[11]

Scallop Kofun [ja] is a kind of kofun defined by a circular body with a small part extending. This can make it an interrmediate between a Keyhole-shaped kofun and a circular-type kofun [ja].^[11]

Famous examples include Hokenoyama Kofun in the Makimuku ruins,^{[12][13]: 249} dated to around 250 AD,^[13]: 253 and Nyotaizan Kofun.

Octagonal Kofun [ja] (八角墳, hakkaku-fun) are a very rare kind of kofun characteristic of Emperors.

Many Japanese Emperors were buried in them including Empress Kōgyoku in Kengoshizuka Kofun,^[14][15] Emperor Tenji in his Mausoleum,^[16] and Emperor Jomei in Dannozuka Kofun^[17][18]

From the end of the 6th century to the beginning of the 7th, the tumuli of the monarchs changed from square hōfun tumuli [ja] to octagonal hakkaku-fun [ja] tumuli.^[19]

• Ise Kofun (Fujioka City) [ja]
• Inari Kofun [ja]
• Oichi No.1 Kofun [ja]
• Kajiyama Kofun
• Kengoshizuka Kofun
• Gobyo Kofun [ja]
• Takei temple ruins
• Dannozuka Kofun
• Tsukamyojin Kofun [ja]
• Nakaoyama Kofun [ja]
• Nakayamasōen Kofun
• King Noguchi Kofun [ja]
• Mitsuya Kofun [ja]
• Yoshida Kofun

zenpō-kōhō-fun [ja] (前方後方墳, two conjoined rectangles kofun) is a kind of kofun shaped somewhat like the more keyhole shaped Zenpokoenfun, but they have a square body rather than a circular one.^[20][21] They tend to be smaller than Zenpokoenfun.^[22] Yanaida Nunōyama Kofun is one of the largest of the type^[23].

There is a specific style exemplified by Yadani Kofun and Jinyama Tumulus Cluster and Rokuji Kozuka Kofun and Tomisaki Kofungun of Ōzuka-Senbōyama Sites as yosumi-tosshutsugata (四隅突出形), which is square or rectangular, with protrusions on each of its four corners; however, it is unique in that it is not a true rectangle, but has a narrow waist, similar to a "two conjoined rectangles" type (zenpō-kōhō-fun [ja] (前方後方墳)). The slope of the mound is covered with fukiishi -like stones, with a row of larger stones marking its edge, and is surrounded by a two-meter wide moat. The yosumi-tosshutsugata style is unique to the late middle Yayoi period and is most prevalent in western Japan in areas influenced by the Izumo culture.^[23]

Joenkahofun [ja] (上円下方墳) is a rare kind of kofun with a round dome top and a square bottom.^[24][25][23]

They are associated with the Asuka Period.^[24][26]

Musashi Fuchū Kumano Jinja Kofun in Fuchū in Tokyo and Miyazuka Kofun are two notable examples.^[23]

• Ishino Karato Kofun [ja]
• Sanno-zuka Ancient Tomb [ja]
• Shimizu Yanagikita No. 1 Tomb [ja]
• Tenmondai Kounai Kofun [ja]
• Nochi Kubo Ancient Tomb [ja]
• Miyazuka Kofun
• Musashi Fuchū Kumano Jinja Kofun

Corridor-type kofun [ja] (横穴式石室, yokoana-shiki sekishitsu) are a kind of kofun dug as artificial caves in Ancient Japan.^[27][28][29]

This list includes the "Mozu-Furuichi Kofun Group: Mounded Tombs of Ancient Japan,"^[30] which was inscribed as a UNESCO World Heritage Site on 6 July 2019.^[31]

• 
  Oyamato, Yanagimoto and Makimuku Kofun Group, Nara Prefecture, 3rd century
• 
  Saki Tatanami Kofun Group and the Heijō-kyō site, Nara Prefecture, 4th century
• 
  Furuichi Kofun Group, Osaka Prefecture, 5th century

• William Gowland, a British engineer who made the first survey for Saki kofun group
• Ernest Satow, a British diplomat who wrote about kofun in Kozuke for the Asiatic Society of Japan
• Fukiishi, stones used to cover kofun
• Kofun system
• Zenpokoenfun
• empun [ja]
• square-type kofun [ja]
• zenpō-kōhō-fun [ja] (前方後方墳)
• hotategai-gata [ja]
• Octagonal Kofun [ja]
• corridor-type kofun [ja] (横穴式石室, yokoana-shiki sekishitsu)
• Joenkahofun [ja]

• 飛鳥高松塚 (Takamatsuzuka, Asuka), 橿原考古学研究所編, 明日香村, 1972.
• 前方後円墳 (Keyhole-shaped kofun), 上田宏範, 学生社, 東京, 1969.
• 前方後円墳と古代日朝関係 (Keyhole-shaped kofun and diplomatic relations between ancient Japan and Korea), 朝鮮学会編, 東京, 同成社, 2002.
• Niiro, Izumi (1992). "V古墳時代 2古墳 a前・中期". Zukai Nihon no jinrui iseki 図解･日本の人類遺跡. Tokyo Diagaku Shuppankai. ISBN 4-13-026200-9.

• Kofun - World History Encyclopedia
• Japanese Archaeology: Kofun Culture
• (In Japanese) Decorated Kofun Database
• Comprehensive Database of Archaeological Site Reports in Japan, Nara National Research Institute for Cultural Properties