How did a prized red gemstone reach the ancient, mysterious Shu kingdom?

In the highest-ranking sacrificial pit at Sanxingdui, 11 crimson beads remained undisturbed for 3,000 years among bronze vessels, ivory tusks and fragments of gold. They are carnelian – a red gemstone prized across the ancient world, from the Indus Valley to the Middle East and the Mediterranean. In China, however, carnelian was not commonly found in elite burials until the late Western Zhou dynasty (c1046-771BC), with red tones traditionally represented by other minerals, such as ochre and...