1. Background: In ancient China, the geographical environment had an important influence on military defense and economic development. Mountains and rivers often become natural barriers in wars and important resources for economic activities such as agriculture and forestry. Therefore, the allusion of "mountains and rivers are outside" reflects China's attention to the geographical environment in ancient times.
2. Source: The mountain and river allusions in the table first appeared in Historical Records Qin Benji. It records that during the reign of King Xiang of Qin Zhuang, the State of Qin attacked the State of Zhao. Because of Zhao's superior geographical environment and mountains and rivers, it was impossible to attack for a long time and finally retreated. Since then, "mountains and rivers on the surface" has become a special vocabulary to describe dangerous terrain, which is easy to defend but difficult to attack.
3. Meaning: The literal meaning of mountains and rivers inside and outside is surrounded by mountains and rivers, with barriers inside and outside and dangerous terrain. It vividly describes that a region has mountains and rivers as a natural barrier, which makes the region have a military advantage that is easy to defend but difficult to attack. At the same time, "mountains and rivers are outside" also means that the geographical environment of this area is superior and it has the potential to develop economic activities such as agriculture and forestry.
Related knowledge of allusions
1. Definition: An allusion is a short story, idiom or quotation, which usually involves historical events, myths and legends, literary stories or folk stories. The content and meaning of allusions often have profound cultural connotations and implications, which can enlighten and educate people.
2. Function and significance: Allusions can convey cultural values and ideological wisdom and help people better understand the development of human civilization. Allusions can stimulate people's imagination and creativity and promote the development of literature, art and other fields. This allusion can also enhance people's sense of cultural identity and national pride and promote social unity and harmony.
3. Application scene: In literary and artistic works, allusions are often used to enrich the content and meaning of the works. In speeches, debates and other occasions, people often cite allusions to support their views and arguments. In addition, in business and education, allusions are often used to convey information and values.