Mozu Tombs in the context of "Kofun Period"

Sakai (堺市, Sakai-shi; Japanese pronunciation: [saꜜ.kai, sa.kaꜜi.ɕi]) is a city located in Osaka Prefecture, Japan. It has been one of the largest and most important seaports of Japan since the medieval era. Sakai is known for its kofun, keyhole-shaped burial mounds dating from the fifth century. The kofun in Sakai include the largest grave in the world by area, Daisen Kofun. Once known for swords, Sakai is now famous for the quality of its cutlery. As of 1 January 2022, the city had an estimated population of 819,965, making it the fourteenth most populous city in Japan (excluding Tokyo).

Zenpokoenfun is an architectural model of Japanese ancient tombs (Kofun), which consists of a square front part (前方部, Zenpō-bu) and a circular back part (後円部, Kōen-bu). The part connecting the two is called the middle part (くびれ部, Kubire-bu), which looks like a keyhole when viewed from above. Therefore, they are also called keyhole-shaped mounds in English, and in Korean, they are called long drum tombs (장고분, Janggobun) due to their resemblance to Janggu, and it is also a form of the Kofun that appeared earlier in the Kofun period along with the enpun [ja] (円墳; lit. circular type). Generally, large Kofun are front and rear circular tombs, widely distributed in Honshu, Shikoku, and Kyushu with Gokishichidō as the center. Among them, the largest front and rear circular tomb in Japan are the Mozu Tombs with a total length of 525 meters. In addition to Japan, there are also the front and rear circular tombs in South Korea, as well as the front and rear circular tombs in Chosan County Ancient Tomb Group and Chasong County Ancient Tomb Group located in North Korea. In addition, Korean archaeologist Jiang Renqiu believes that the Songhe Dong No. 1 Tomb (Wuyishan Mountain Kofun) located in Goseong County, South Gyeongsang Ancient Tomb Group, is the Zenpokoenfun.