Answered by Arnold from France | Mar. 15, 2016 20:00
For all I know, it was opened up by an official named Zhang Qian during Han Dynasty, who was sent on a diplomatic mission to the western regions. He completed his mission perfectly and the communication between the central plain and the western regions improved. Numerous merchants in east and west regions followed the path he walked, exchanging products and ideas. The major China's product transported along the route was silk, hence the name.