It is believed that it was through this trading network that tea (typically tea bricks) first spread across China and Asia from its origins in Puerh county, near Simao Prefecture in Yunnan.
The route earned the name Tea-Horse Road because of the common trade of Tibetan ponies for Chinese tea, a practice dating back at least to the Song dynasty, when the sturdy horses were important for China to fight warring nomads in the north. Source: Wiki.
Below is a 3-part video on this ancient trade route that brought puerh tea to the rest of the world.
http://youtu.be/oWnRI5K7cuA Part 2
http://youtu.be/psQwXZCu6ZE Part 3
A song which was dedicated to all the war orphans during the war with the Japanese, encouraging them to move on and instead of suffering their losses to actively contribute to humanity. A very moving song.