Photo/Illutration A wooden structure believed to be a bulkhead of a Mongolian battleship in the Yuan Dynasty’s 1281 invasion of Japan (Provided by the municipal education board of Matsuura)

MATSUURA, Nagasaki Prefecture—Artifacts discovered on the seabed off Takashima island here were confirmed as parts of a shipwreck from the 13th century Mongol invasion of Japan.

The findings included wooden structures believed to be bulkhead parts and the hull of a battleship that belonged to the fleet of the Yuan Dynasty, according to an Oct. 11 report by the municipal board of education.

Archaeologists also uncovered a sword and porcelain fragments at the same location.

This marks the third confirmed shipwreck found from the 1281 Battle of Koan.

The Mongol empire under Kublai Khan had previously tried to invade Japan in 1274 in the same region. Both attempts failed, after seasonal storms devastated thousands of Mongolian ships stationed offshore.

The first and second shipwrecks from the 1281 attack were identified in 2011 and 2015, respectively.

Parts of the third ship were first discovered in October last year in waters about 18 meters deep and 50 meters south of the second shipwreck site.

During the initial excavation last fall, archaeologists uncovered wooden structures ranging from 2 to 5 meters in length, along with fragments of Chinese porcelain dating from the late 13th to early 14th centuries.

After analyzing these items and additional objects found this month, researchers concluded that this site is another shipwreck location from the Battle of Koan.

Remains from the Mongol invasions are believed to be scattered across a vast seabed area of 1.5 million square meters off the island.

Of this area, 384,000 square meters became Japan’s first nationally designated underwater archaeological site in 2012, after the first shipwreck was discovered.

The second and third ships were both found outside the eastern boundary of the designated site.