No mention of the Japanese government finding this stuff elsewhere and planting it like it belonged their yet?
To me it is like finding more Dead Sea scrolls under the Belagio Las Vegas.
Sailors sail. Anywhere they can go.
Archaeologists never seem to understand this. Possibly none of them own a boat.
Most likely a tourist just from Italy accidentally on purpose dropped those coins there.
The China connection is the most likely source but the Portuguese were in Japan in the early 15th century. Neither were too scrupulous and either might have dumped a load of worthless old coins off on unsuspecting Okinawan merchants.
Interesting. It has to be noted that the coins were 3rd Century and the Castle is 12th + century. Plenty of opportunity to get to Japan over the ancient trade routes and via China.
The Silk Road had an extension across the Japan Sea. These coins could easily have been carried to Sakai during the Kofun era (300-550 AD), and from there somehow found their way to Okinawa some time in the succeeding 1000 years or so.
I am reading a book on the Roman Indian Ocean & West Africa trade. It’ s a hot new area in Roman history & archeological research.
High labor costs and excessive regulation drove Roman coin production off-shore.