Historical introduction: According to Sima Qian's "Historical Records: The Sixth Annals of the First Emperor of Qin": "The First Emperor of Qin destroyed six kingdoms and divided the world into thirty-six counties, with one method, chariots on the same track, and books with the same characters, from the east to Haiji North Korea extended from Lintao and Qiangzhong to the west, to Beixiang (Xiang)hu in the south, to the north by the river, and from Yinshan to Liaodong. Its territory was unprecedentedly large, and it was the beginning of the unification of China. The emperor was only forty years old, and his achievements were shining brightly. He was satisfied with his achievements and wanted to show off his achievements. So from the twenty-seventh year to the thirty-seventh year, he visited the country many times, from Longshan to the north. It stretches from Haiyu in the east to Kuaiji in the south. All the important places are engraved with stones to commemorate the merits of the Qin Dynasty. Langyatai is one of them."