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

In the highest-ranking sacrificial pit at Sanxingdui, 11 crimson beads lay 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 Chin