In short, what are the characteristics of the distribution of ancient castles in the northern and southern foothills of Yinshan Mountain?

It presents an open and low face, as if to be integrated with the earth. Sometimes because of the shade of trees, people can't see their true colors until they are in front.

In 127 BC (the second year of yuanshuo), Wei Qing was sent to capture Yinshan Mountain and its southern Hetao area, and Shuofang County and Wuyuan County were set up to restore and rebuild Qin Changcheng as an important strategic facility for the northern border defense. The Huns didn't stop there. They often attack suddenly and enter the border counties within the Great Wall to kill and plunder.

The image characteristics of "Yinshan" are: it's very cold, and in August, the snow is all over the sky, which makes people feel dazzling at first sight; It is majestic and steep, and at the same time, there is no lack of handsome, bright moon, clouds around; It is full of vitality, and you can also see "mu" and "people" here, with traces of human activities; It was born with extraordinary momentum, and the mountains in the south of the Yangtze River could not be compared with it.