The Han Dynasty cleared The Hexi corridor near modern Afghanistan, setting the stage for The Silk Road
The Silk Road is an old obsession of mine. I just finished a superb new book on it.
For decades and centuries, the frontiers of China were the home to the Xiongnu, a confederacy/alliance of nomads who lived within the shelter of the towering Parmir Mountains. In the early days, the Xiongnu would emerge and attack border settlements in China, so the Han Dynasty began paying the nomads not to attack (a common theme in human history). Generally, the payment was in silk, and over time the payments grew quite substantial. Finally, the Han Dynasty had enough. New generals emphasized new strategies (such as increased calvary) to hunt the nomads in the mountains, and the Xiungnu were nuetralized. This secured the Hexi Corridor near modern Afghanistan, and set the stage for the beginnings of The Silk Road.