Qinling is the north-south wind boundary of China, the temperature, climate and terrain of the north and south have different changes, so the Qinling-Huaihe line has become the most important north-south dividing line in China's geography. In winter, Qinling blocks the cold tide to the south into the southern region; in summer, blocking the wet sea breeze to the northern region. Qinling and Huaihe River basins are the transition areas between rainy in the south and dry in the north. From the Qinling and Huaihe River to the north, the rainfall has decreased sharply.