More than 600 artifacts have been recovered from the sunken vessels, which date back to the Ming Dynasty (1368-1644), according to the Tianjin Cultural Heritage Protection Center. The wrecks first came to light in April, after workers dredged a section of the canal in the northern municipality of Tianjin, said Mei Pengyun, director of the center. After the month-long excavation, experts revealed fragments of one ship and the well-preserved structure of another. A large numbers of bricks, ceramic pieces, bone and wooden wares were found scattered around the site, Mei added. The second ship, measuring 13 meters long, is believed to have been a barge that once plied the 1,776-km canal, which stretches through several provinces in north and east China.