Gansu province, located in Northwest China, is home to the Hexi Corridor, a narrow stretch of traversable plains west of the Yellow River. It was the only route from the Central Plain of China to the west and eventually to Central Asia during ancient times. It was also part of the ancient Silk Road.
The main purpose of the Great Wall that was built here was to maintain the central Plain’s active and dominant position in military affairs, and to safeguard peace in the region to ensure the passage of traders and travelers.The total length of the existing Great Wall in Gansu is 3,654 kilometers, ranking second in China, including the Great Walls of the Qin (221-206 BC), Han (206 BC- AD 220) and Ming (1368-1644) dynasties.
Undoubtedly the most iconic of Gansu's Great Wall relics is Jiayu Pass, the western terminus of the Great Wall of the Ming Dynasty.The pass is located in the middle of a narrow valley, the choke point of the Hexi Corridor and the Silk Road. It is also the most magnificent and best preserved military defense castle on the Ming Great Wall.
It consisted of three defense lines: an inner fort, an outer fort, and a moat. The fort is trapezoid-shaped with an total area of more than 33,500 square metres. The wall is 733 meters long and 11 meters high.
There are two gates: one on the east side of the pass and the other on the west side. Next to each gate, there is a building. The south and north sides of the pass are connected to the Great Wall. A turret was built on each corner of the pass. On the north side, inside the two gates, there are wide roads leading to the top of the pass. Jiayuguan was first built in 1372, the fifth year of the Hongwu reign of the Ming Dynasty, and completed in 1540 after 168 years of construction.
Two other important passes along the Ming Great Wall, Juyong Pass in Beijing and Shanhai Pass in Hebei province, have both been referred to as the "First Pass under Heaven". In contrast, Jiayu Pass in Gansu has been widely referred to as the "First and Greatest Pass under Heaven”.
In addition, the western end of the Qin Dynasty Great Wall is in Lintao county, and the western end of the Han Dynasty Great Wall is in Dunhuang, both of which are in Gansu province. In other words, Gansu contains all the three western ends of the Great Wall of three dynasties of China, which reflects the particularity of Gansu's geographical position in history.