Bamboo slip and infrared image
As part of a push to expand their empire into Central Asia in the second century b.c., the rulers of China’s Han Dynasty (206 b.c.–a.d. 220) established a string of postal stations in a narrow pass between the Tibetan and Mongolian Plateaus known as the Hexi Corridor. Each station was home to a fleet of around 40 horses tasked with carrying missives across this frontier territory. The postal horses were generally steppe ponies that were significantly smaller