Ancient Roman Coins Found Beneath Japanese Castle

The find catches researchers by surprise, as they ponder how the artifacts ended up on Okinawa.

Photo: A 4th-century copper coin from ancient Rome was among the finds on Japan's Okinawa island.

Japanese archaeologists said on Wednesday they have for the first time unearthed ancient Roman coins at the ruins of an old castle.

The discovery of 10 bronze and copper coins -- the oldest dating from about 300-400 AD -- in southern Okinawa caught researchers by surprise.

It was the first time Roman Empire coins have been discovered in Japan, thousands of kilometers from where they were likely minted.

"At first I thought they were one cent coins dropped by US soldiers," archaeologist Hiroki Miyagi told AFP.

"But after washing them in water I realized they were much older. I was really shocked."

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The sub-tropical island chain hosts a cluster of US military bases and thousands of troops.

A team of researchers have been excavating Katsuren castle, which is a UNESCO world heritage site, since 2013.

An X-ray analysis of the dime-sized coins showed some were embossed with Roman letters and possibly the image of Emperor Constantine I and a soldier holding a spear.

Several others dated from a later period -- the 17th century Ottoman empire.

Researchers were left scratching their heads about how the coins ended up at the castle in faraway Okinawa, which was built sometime in late 13th or early 14th century and abandoned about 200 years later.

It was once the residence of a feudal lord, whose wealth was linked to regional trade but he was not known to have had business ties with Europe.

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"East Asian merchants in the 14 and 15th centuries mainly used Chinese currency, a round coin with a square hole in the middle, so it is unlikely that the Western coins were used as a means of currency," said Miyagi, who also teaches at Okinawa International University.

"I believe they probably got the coins in Southeast Asia or China."

VIEW PHOTOS: Ancient Roman Mosaic Revealed

Italian archaeologists digging in a small Tuscan village have unearthed part of what they believe is a large and impressive ancient Roman mosaic. The artwork lies in a private property next to a local road in the village Capraia e Limite.

Ancient Roman Mosaic Found in Tuscany

One mosaic, dating to the second half of the 4th century AD, shows geometric patterns framed by floral motifs. The other, dating to the 5th century AD, boasts octagons decorated with animals, flowers and a human bust.

Villa Owned by Ben-Hur's Rival Identified

The large mosaic graced the floor of a luxurious Roman villa that stood in the Tuscan countryside for four centuries, from the 1st to the beginning of the 6th century AD. Evidence of the villa was first found in 1983, when workers digging to build an orchard unearthed an inscription mentioning one of the owners of the complex. It read: Vettius Agorius Praetextatus, referring to one of the most famous pagan senators of the later 4th century AD.

Photos: Excavating an Ancient Villa

In the beginning of the 6th century AD, the villa was completely abandoned and plundered of any material that could be recycled. Luckily, the floor mosaics could not be removed. Excavations in 2013 brought to light a stunning oval mosaic with a wild boar hunting scene which dates to the second half of the 4th century AD. Because of legal issues and lack of funding, the mosaic was covered soon after its discovery in order to preserve it.

1500-Year-Old Mosaic Map Found

The finding prompted new investigations. Archaeologists Lorella Alderighi of the Archaeological Superintendency of Tuscany, and Federico Cantini of the University of Pisa, speculated the floor mosaic extends further. In fact, parts of two floor mosaics came to light.

The older mosaic consisted of geometric patterns framed by red decorations with acanthus and vine leaves in various shades of grey, blue and black.

The other mosaic, dating to the 5th century AD, displayed scenes with animals, flowers, geometric patterns framed by octagons. At the center of one of the octagons is the bust of a man with a tunic and large eyes.

According to the archaeologists, the investigated portion of the villa had an hexagonal structure with rooms opening onto a central hall.

The archaeologists estimate the size of the floor mosaic to be about 300 square meters (984 square feet). They only have unearthed one-eighth of it. Unfortunately, most of the mosaic lay beneath an industrial shed. Although the archaeologists believe the artwork is still intact, it's unlikely it will be brought to light in the near future.

The newly unearthed mosaics have been already covered for preservation -- like the mosaic with the hunting scene. Alessandro Giunti, mayor of Capraia e Limite, said that at least one mosaic, the one featuring the wild boar hunting scene, will be restored and displayed in the near future.