The Shimbaru-Nuyama Mounded Tomb Group, which was constructed from the 5th to the 6th centuries, offers tangible evidence concerning the Munakata clan who sustained the living tradition of worshipping Okinoshima.
The Munakata region forms an integrated sea space that links Kyushu, where a large sea inlet once existed, with Okinoshima, and with Oshima, which is situated between them.
The Shimbaru-Nuyama Mounded Tomb Group is located beside the agricultural land that was once a sea inlet, on a plateau overlooking the sea that stretches out toward Okinoshima.
It consists of both large and small burial mounds, including keyhole-shaped, round, and square mounded tombs built close together along the plateau.
These tombs bear witness to the lives of members of the Munakata clan, who played a key role in overseas exchanges and nurtured a tradition of worshipping Okinoshima.
Okinoshima have been preserved almost intact to the present day because of their geographical location, which defies easy access, and local religious traditions such as strict taboos that protect the sacred island. The ancient faith in Okinoshima survives to this day.
Okitsu-miya Yohaisho, which had been built on the northern shore of Oshima by the 18th century, is the place from which to worship Okinoshima, since people are not normally allowed to visit the island. It functions as a hall for worshipping the sacred island from afar.
The Munakata Daiguji (high priest) family, which prospered through its engagement with international trade, continued the tradition of worship at Munakata Taisha when ancient rituals were no longer performed there.
Even since the family's lineage was interrupted at the end of the 16th century, priests and local people have supported the tradition to this day. The people of Munakata have long fished the waters near Okinoshima, and guards were stationed on the island from the 17th century onward to protect its ocean boundaries; yet customs such as taboos strictly forbidding ordinary people from delivering or removing any object to or from the sacred island have continued to be respected. Some taboos still survive today.