Construction of the Great Wall: In the long history of China, many feudal dynasties built the Great Wall many times to consolidate their rule; In ancient China, thousands of working people in Qian Qian contributed wisdom and blood to it, making it a wonder of the world. Both the dragon-shaped city wall and the throat artery reflected the war thought of building a city at that time, and also marked the high achievement of architectural technology at that time. For example, during the Ming Dynasty, with the high development of feudal economy, the construction industry also embodied a huge production process and a relatively scientific brick and tile firing workshop. Therefore, the output of brick products has greatly increased, and bricks are no longer precious building materials, so the inner and outer eaves of many places in the Great Wall of Ming Dynasty are built with giant bricks. Under the conditions of manual construction and manual handling of building materials at that time, it was not only convenient to build the city wall with bricks with small weight and the same size, but also improved the construction efficiency and building level. Secondly, the gates of many passes are long-span arches made of blue bricks. Some of these blue bricks have been severely weathered, but the whole gate is still magnificent, showing the superb skills of building arches at that time. Judging from the architectural decoration of the Guanta Tower, many stone carvings and brick carvings are extremely complicated and elaborate, reflecting the artistic talent of craftsmen at that time. The city wall is the main part of the city wall, with an average height of 7.8 meters, and some sections are as high as 14 meters. Where the mountain is steep, the building is low, and the flat place is high; The key places are higher, and the general places are lower. The wall body is the main part of defending the enemy, with a relatively wide total thickness, a foundation width of 6.5 meters and an average floor width of 5.8 meters on the wall, so as to ensure that the two wagons run in parallel. The wall is composed of an outer eave wall and an inner eave wall, filled with soil and gravel. The cornice wall refers to the side of the skin wall facing the city. There are obvious points when building, generally 25% of the wall height. The separation of the wall can increase the width of the lower part of the wall, enhance the stability of the wall, strengthen its defensive performance, and make the outer wall magnificent. The inner cornice wall refers to the inner side of the outer skin wall, which is generally constructed as a vertical wall without obvious points. As for the thickness of the outer cornice wall, the thickness of the wall at the "crib" shall generally prevail. The thickness here is generally one and a half bricks wide, and it gets thicker as it goes down. Bricklaying method is mainly flat masonry. The structural content of the wall depends on the local climate conditions. Generally speaking, the construction methods of the Great Wall can be divided into the following types: rammed earth wall; 2. Adobe wall; 3. Blue brick wall; 4. stone wall; 5. Mixed masonry; 6. striped stone; 7. Clay connecting bricks are used to build walls, which are made of bricks, stones and mixed masonry. When the terrain slope is small, build bricks.
The historical function of the Great Wall: The Great Wall belt, which is composed of the vast northern and southern regions and mediated by the Great Wall of Wan Li, runs through a considerable part of Liaoning, Inner Mongolia, Ningxia, Gansu, Shaanxi, Shanxi, Henan, Hebei, Beijing, Tianjin, Shandong, Jilin, Heilongjiang, Qinghai, Xinjiang and other provinces (cities, autonomous regions), including the Mongolians in today's history. Its range is hundreds or even thousands of kilometers wide from north to south and thousands of kilometers long from east to west. The Great Wall Belt has been inhabited by many ethnic groups since ancient times, and the development of ethnic groups and their relations is the key to observing and understanding everything in the Great Wall Belt. In the course of historical development, some ancient ethnic groups in the Great Wall Belt disappeared, and some new ethnic groups merged and formed, all of which are closely related to more than 20 ethnic groups distributed in the Great Wall Belt today. All ethnic groups, whether they have disappeared or continue to develop today, have made important contributions to the historical development of China. The Great Wall of Wan Li is the product of the development of ethnic relations in ancient China, but at present, the research on the internal development law of ethnic relations between the north and the south of the Great Wall is not sufficient. Summarizing the existing research results, broadening the research fields and revealing the internal relationship between the Great Wall and the development of ethnic relations in China are of great practical significance and theoretical research value for the study of the Great Wall, ethnology and the development of the history of ethnic relations in China.