Pottery figurines of a Sogdian caravan on the Silk Road, on display in Hong Kong. [Photo by Li Yibo/Xinhua/Roy Liu/For China Daily]

"The Silk Road is not merely a conduit for commerce, and what was being transported along it should never be simply viewed as goods. Culturally and artistically it enabled a cross-pollination whose seeds were blown far and wide along the extended route.

"For the Chinese, the road is an eyeopener: the existence of an outside world was made known to them, in an intriguing and sometimes intimate way. Ever since Zhang Qian's adventure, the official history of every Chinese empire features a section headed 'the Chapter of Xiyu'."

To ensure that the road was safe and passage unhindered, successive Chinese emperors installed along it a defense, control and postal system, of which the painted courier image mentioned at the beginning offers a salient example.