The US government has returned to Thailand hundreds of ancient artifacts looted in the early 1970s from Ban Chiang, an important Neolithic settlement and burial ground in northeast of the country, Voice of America reports. The artifacts were found in 2008, during a raid on the Bowers Museum in Santa Ana, California, after a five-year federal investigation. The museum agreed to return the items in exchange for none of its staff facing criminal charges.

The collection of pottery, bronze items, stone tools, beads, and sandstone molds was returned yesterday, during a ceremony at Thailand’s National Museum in Bangkok. US Chargé d’Affaires, W. Patrick Murphy, handed the artifacts to Thailand’s culture minister, Veera Rojpojanarat.

“Of the artifacts returned to Thailand, we can say that the 554 pieces, most of them are priceless because they are dated to a pre-historic period,” Rojpojanarat declared during a press conference.

Most of the pottery vessels have suffered damaged and are showing cracks, and many bronze and stone tools are broken. But Thai experts say the objects are valuable and useful for academic purposes, and will allow for a new understanding of ancient settlers, including the materials they used in the production of tools and art pieces.

According to Voice of America, three other art museums and two antiquities dealerships in California were also raided during the 2008 operation. Several people allegedly involved in an antiquity smuggling network from Thailand, Cambodia, and Burma, face criminal charges.

During the press conference yesterday, Murphy said that the US had already returned some 7,000 cultural artifacts to 30 countries, most recently Cambodia and Mongolia.