An archaeologist checks ivory artifacts at the Sanxingdui Ruins site in Guanghan, Sichuan province. (Photo: Xinhua)

Archaeologists work in one of the pits at the site. (Photo: China Daily)

Undated photo provided by the Sanxingdui Ruins sacrificial pits archaeological project shows a partial gold mask unearthed from the Sanxingdui Ruins site in Southwest China's Sichuan province. (Photo: Xinhua)