Introduction to the Hanguan Ancient Road: The Hanguan Ancient Road crosses Hengling Mountains, with a total length of 15 miles. It is the only way from Luoyang to Chang'an in ancient times. The valley is 50~70 meters deep, the valley bottom is about 10 meters wide, and the narrow part is only 2. 3 meters, the slope of the valley bank is 40 to 80 degrees. The bottom of the valley is connected by winding roads. It is rugged and narrow, and the empty valley is deep. When walking in it, as if entering a letter, on both sides of the pass, there are steep cliffs, numerous peaks and rocks, the terrain is dangerous, and the landscape is forested. It is easy to defend but difficult to attack. It is said to be "one man can guard the pass, but ten thousand men cannot open it". Some people also use "one mud pill and east to seal Han Valley" to describe its strategic position.