It's believed to be a first — and it certainly came as a surprise: Ancient Roman coins have been found in the ruins of a castle in Okinawa, Japan, that dates to the 12th and 15th centuries. The copper coins were found in 2013; X-ray analysis shows that they bear an image of Constantine the Great.
The four Roman coins were found at the Katsuren Castle — a World Heritage Site in Japan's southwestern city of Uruma. The excavation was carried out by the local board of education, which says the find hints at the region's wide trade ties.
From The Japan Times:
"Okinawa's trade with China and Southeast Asia was thriving at the time and the finding is 'precious historical material suggesting a link between Okinawa and the Western world,' the board of education said.
"Each coin measures 1.6 to 2 cm in diameter. The designs and patterns on both sides are unclear due to abrasion."
Another coin that was found at the site is believed to be from the Ottoman Empire — whose dates overlap more closely with the castle that thrived in Okinawa when the island was known as Ryukyu, as Japanese news outlet NHK reports.
The broadcaster adds that the coins, which are now on display at a museum in Uruma, may be the first from either Rome or the Ottoman Empire that have been found in Japanese ruins.