Here is a history of Chinese power expanding to the Western Regions.
The Silk Road primarily refers to the terrestrial routes connecting East Asia and Southeast Asia with East Africa, West Asia and Southern Europe. In June 2014, UNESCO designated the Chang'an-Tianshan corridor of the Silk Road as a World Heritage Site.
The pass is located at the narrowest point of the western section of the Hexi Corridor, 6 kilometres (3.7 mi) southwest of the city of Jiayuguan in Gansu. The structure lies between two hills, one of which is called Jiayuguan Pass. It was built near an oasis that was then on the extreme western edge of China.