occultist points to esotericworld:

At over 3,000-years-old and discovered as recently as 1987, Sanxingdui is perhaps the most enigmatic culture revealed from ancient China. There are no writings, historical records, or even myths of this unique civilization. The only information archaeologists have are the visually striking artifacts that have been found. An entire museum has been dedicated to the findings at Sanxingdui. The jade, bronze and gold statues and masks are created in a style unlike anything else seen from that time or region. 

History is a mystery.

A few links for digging into the mystery of the Sanxingdui culture:

• Sanxingdui (Jimmy Wales Project)
• “The Finds at Sanxingdui” (nga.gov)
• “Sanxingdui mask relics record traces of Bronze Age” (chinadaily.com.cn)
• “History Wonders of Sanxingdui” (china.org.cn)
• Sanxingdui Museum (chinamuseums.com)