Today I am traveling along the coastal region of Oita Prefecture while researching the Amabe (海部), considered to be one of the largest ancient maritime clans. Although most of their traces have been lost today, in ancient Japan they were indispensable in the transmission of people, goods, and information, playing a crucial role in people’s lives and in the structures of power. The Amabe were closely related to the Kaifu clan（海部氏）that I recently researched in Tokushima Prefecture, but since this region was once called Bungo Province, they are positioned as the Bungo Amabe. By tracing these maritime clans that lived across the sea from each other in Bungo and Shikoku, we can pursue the traces of history that have been swallowed by the sea of ancient Japan.
Among them, one of the most important strongholds of the Bungo Amabe is the Kamezuka Kofun in the eastern part of Oita City. The Kamezuka Kofun is a massive zenpō-kōen-fun about 116 meters long, constructed on a hilltop plateau with a commanding view of Yamaguchi Prefecture and Shikoku. It is an enormous and imposing zenpō-kōen-fun, and according to the Bungo no Kuni Fudoki, this entire area was once called Amabe District（海部郡）.