The Great Wall is a symbol of the Chinese nation and a miracle of human civilization. The famous saying "You are not a hero until you reach the Great Wall" is well known in China. When it comes to China, we can't help but mention the Great Wall of Wan Li, China; When you come to China, you must go to the Great Wall of Wan Li. It is true that the Great Wall is known as the length of Wan Li, but there are different opinions about where the Great Wall begins and ends. Because the construction of the Great Wall took more than 2,000 years from the Qin Dynasty to the Qing Dynasty, and there were many fractures, many places built in the early days were damaged, which led to many disputes about the geographical problems at both ends of the Great Wall. The first statement is based on historical records? "Biography of Meng Tian" has the following evidence: "The merger of Qin and the world made Meng Tian drive 300,000 people from the north to Rongdi, take Henan (now south of Hetao in Inner Mongolia) and build the Great Wall. Because of the dangerous terrain, the traffic was blocked by soldiers, stretching for more than 10,000 miles from Lintao to Liaodong." According to this sentence, the Great Wall built by Qin Shihuang has one end in Lintao and the other in Liaodong. Qin Shihuang built three sections of the Great Wall. The eastern section begins in Dehua County, Inner Mongolia, and extends eastward along the border between Inner Mongolia and Hebei. It turns southeast in Liaoning, and then winds to the north bank of Datong River in Pyongyang, North Korea. The destination is what we call Liaodong. The middle section of the Great Wall starts from Xinghe County, Inner Mongolia in the east, swims between Yinshan Mountain and Hetao of the Yellow River, and reaches the northern section of Wulanbuhe Desert in the west. The investigation confirmed that the western section starts from Min County, Gansu Province in the west, meanders northward along the east bank of Taohe River to Lintao County and Lanzhou, and then extends eastward to Yuzhong County. Experts believe that today's Min County was called Lintao County in Qin Dynasty, and the western end of Wan Li Great Wall in Qin Dynasty was in Lintao County. But now the monument next to its site says "Warring States Great Wall Site". During the Spring and Autumn Period and the Warring States Period, the Great Wall was built in various vassal states including Qin. This section of the Great Wall was built by King Qin Zhao and restored by Qin Shihuang. Unfortunately, the time is too long, which makes people doubt the authenticity of its existence, because it is difficult to see the city wall between Shan Ye. In order to find out whether the Great Wall ever existed here, some people spent decades looking for it, trying to find some traces of spider silk and horses. They found many relics of the Qin dynasty, but this is not enough to prove the existence of the Great Wall, because this was originally the activity area of the Qin dynasty, and it is normal to find the relics of the Qin dynasty. The second theory is that the Great Wall of Wan Li starts from Lop Nur in Xinjiang in the west and ends in Liaodong in the east. This statement is based on the Great Wall built in the Han Dynasty. Xiongnu, northern nomadic people, the rise of the Han Dynasty, invaded the border of the Han Dynasty many times. Therefore, Emperor Gaozu Liu Bang was defeated. After seven days and seven nights of siege, he finally escaped with the help of counselor Chen Ping. Because of the border problem, the country was weak in the early Han Dynasty. In order to protect itself, it paid tribute to the Xiongnu every year, but there were still riots on the border. Several emperors in the early Han Dynasty had been practicing the policy of recuperation, and by the time of Emperor Wu of the Han Dynasty, the country was unprecedentedly powerful. With the strength to compete with Xiongnu, Liang Wudi sent generals Wei Qing and Huo Qubing to hit Xiongnu hard. The two sides have been at war for many years, and the passage between Hexi Corridor and Lop Nur in Xinjiang has been opened, and the countries in the western regions have also surrendered to the Han Dynasty. Emperor Wu of the Han Dynasty carried out large-scale construction of the Great Wall while taking military strikes. During his reign, he built four large-scale Great Wall. In 127 BC, after repelling the invading Xiongnu, the northern defense line of Xiongnu was pushed northward to the former Qin Shihuang Great Wall at the southern foot of Yinshan Mountain in Inner Mongolia. The second construction took place in BC 12 1 year. Within a few years after the defeat of the Huns who occupied the Hexi Corridor, the Great Wall was built between Yongdeng County and Jiuquan, Gansu Province, and the eastern end was connected with Qin Changcheng. From BC 1 1 1 to BC 109, Emperor Wu of the Han Dynasty built the Great Wall from Jiuquan to Yumenguan. The last time the Great Wall was built was in 104 BC, and it took three years to build the Great Wall between Yumenguan and Lop Nur in Xinjiang. So, can it be said that the western end of the Great Wall is in Lop Nur? The Great Wall from Hexi Corridor to Lop Nur in Han Dynasty is different from the past. There is no connected wall between the separated pier and beacon tower. But it should also play the role of garrison and convey the enemy's situation. If this is not the Great Wall, how to define this barrier? The third argument is that the two ends of the Great Wall are Shanhaiguan in the east and Jiayuguan in Gansu. These two halls are magnificent, and there is no great damage in history. After many repairs, the East and West confront each other, which can be regarded as the two ends of the Great Wall of Wan Li. According to this statement, it is actually the two ends of the Ming Great Wall. The Great Wall was built on a large scale again in the Ming Dynasty, and it has been built for more than 200 years, because serious border troubles plagued the emperors of the Ming Dynasty. Powerful forces around threatened the rule of the Ming Dynasty at all times. In order to defend its frontier, the Ming Dynasty used a lot of manpower and material resources to build this natural barrier every year. Zhu Yuanzhang entered Beijing, overthrew the rule of the Yuan Dynasty and established the Ming regime. The Yuan regime did not completely collapse at this time, but retreated from Beijing to the north of the Great Wall. It still controls the vast area from Hulunbeier Lake in the east to Tianshan Mountain in the west, the upper reaches of Irtysh River and Yenisei River in the north and the Great Wall in the south. Moreover, the rulers of the Yuan Dynasty did not give up hope and never forgot to defeat the Ming regime and return to the Central Plains. There are a large number of military regimes in Shaanxi, Gansu and Liaodong, which are eyeing the rulers of the Ming Dynasty, and Ming Chengzu is very uneasy about this. In the middle and late Ming dynasty, the powerful Jurchen regime gradually rose in the north, posing a great threat to the rule of the Ming dynasty, and the project of building the Great Wall became more and more huge. Some people think that the Great Wall of Wan Li starts from the Yalu River in Liaodong in the east. The Great Wall built from Shanhaiguan to Liaodong suffered great damage, so the well-built section from Jiayuguan to Shanhaiguan in Ming Dynasty was regarded as the Great Wall of Wan Li. It is still inconclusive where the Great Wall of Wan Li began and where it ended.