The ancient Chinese “postman” depicted without a mouth 

In ancient China, the postal system was established to facilitate the delivery of correspondences and promulgation of state degrees. A pictorial brick, created during the reign of the Wei and Jin dynasties (220-420) and unearthed in 1972 from a tomb in Jiayuguan, Gansu province, China, depicts the prototype of the postman -a Chinese herald-messenger of the time. The intriguing feature of the herald riding a galloping horse and holding a wooden pass is the lack of a mouth, indicating the confidentiality of his mission.
The pictorial brick is one of the gems of the Gansu Provincial Museum.
It’s worth mentioning that the current depiction of the messenger riding a horse became the iconic symbol of the China Post in 1995.