Ukikunden is an archaeological site located near Karatsu in Kyūshū, Japan.^[1] It is a transitional Jōmon-Yayoi site and one of the few Jōmon sites where grains of rice have been uncovered. As a result, some archaeologists speculate it may have been inhabited by Jōmon people rather than Yayoi people.^[2] It contains a noble burial site^[1] at which bodies were interred with bronzes in large urns, as is typical for Yayoi burials.^[3] 63 bronze objects have been found there from the middle Yayoi period,^[4] alongside jadeite magatama.^[5]

The site features notable evidence of the history of agriculture in Japan,^[6] and some models use the area as the origin point of Japanese agriculture.^[7]

Ukikunden is located in Kyūshū. It was discovered beneath a paddy field near the dolmen sites in Morita and Setoguchi. An excavation in 1966 uncovered the long capstone of this dolmen along with significant artifacts such as large urns, jewelry, and bronze weapons. This discovery offers insights into the burial practices and material culture of its time.^[1]

The site gives insight into the history of rice cultivation in Japan, and how cultivated rice breeds changed over time.^[6]

Over 600 burnt rice grains were discovered at the site. AMS dating attributed the grains to the site's Yusu 1 period at end of the 9th century BC, which coincides with the rise of the Yayoi culture.^[6] DNA analyses classified these grains as primarily of the tropical Japonica variety. Later, grains from the 6th century BC and 5th century BC found at other sites like Arita and Fukuoka were identified as temperate Japonica.^[6]

Research by Nobuyuki Kamijo indicated that rice grains from the early Yayoi period at the Ukikunden site were varied in size, tending to be smaller. Later in the early Yayoi period, rice had changed its form, resulting in a more consistent, rounder, and medium-sized grain.^[6]

Archaeological evidence from the site has been influential in Japanese archaeology and in understanding the history of agriculture in Japan. It demonstrates how rice strains were selectively bred and improved over time.^[6]

The Ukikunden site provides insight into burial customs from the Middle to Late Yayoi period. The tombs at Ukikunden do not always have the same number of burial goods. This difference is seen across various kamekan burial urn phases. Coastal areas near Asia do not always have the most burial items. This is true even for bronze mirrors during the KIIa and KIIb phases.^[8]

In Ukikunden, tombs with goods and mirrors are found from KIc to KIIIa phases. There are no goods in the KIIIb phase. The Mikumo-minami-shōji tombs 1 and 2 in Itoshima have most of the goods. This change shows that influence moved from Karatsu to [toshima].^[8]

Leaders in the area did not always share burial items widely. This suggests they did not use goods to gain control over others. This pattern is most clear in the KIc, KIIa, and KIIIc phases. The tombs from KIc and KIIa phases show a clear structure. There is a main burial site with many rich tombs. Only one of these tombs has a mirror. Around this main site, there are smaller sites. Each has only one tomb with goods, but no mirrors.^[8]

The excavated capstone has since been relocated to the Nabatake site, located at the heart of Karatsu city, which is approximately 7 km away from its original location.^[1]

• Proto-Jōmon period
• Miura Peninsula
• Inaridai Sword
• Hashihaka Kofun
• Makimuku ruins
• Inariyama Kofun
• Ichinoyama Kofun
• Inaridai Kofun Group