No trace of human sacrifice has been found at the Guo state burial ground, he says.

So behind the plethora of jade ware was a profound social and ideological change that had been underway for centuries.

In fact, the earliest attempt to codify the use of jade had arguably been made by a man commonly known today as the Duke of Zhou. Acting as a powerful regent for his young nephew after the death of his elder brother, the founder of the Western Zhou Dynasty, the duke, believed to be a prolific author with humanistic ideas, wrote the book Rites of Zhou to expound on his theories on bureaucracy and the state organization.

Somewhere in his writing, which partly dealt with state etiquette and ceremonies, the duke came up with the concept of "the six archetypes of ritual jade". Topping that list is the jade bi, or disc, found in abundance in ancient tombs throughout the first millennium BC.

Although the use of ritualistic jade decreased considerably after the end of the Han Dynasty (206 BC-AD 220) in the third century, the popularity of bi, with its universally embraced round form, endured, partly through a strong appreciation of the country's cultural history, including its jade history, that started to develop later.