People are sensitive to the differences among dialects, and the relevant phenomena have been recorded all over history, such as “people from various areas have different dialects, customs, and interests” (Book of Rites), “old and modern languages are different, and dialects in various areas are different too” (Analects of Confucius), and “The ancient Wu and Yue languages have been absorbed into the southern dialects, while the languages of the Yi and Xia minorities have also  integrated into the northern dialects” (Yánshì jiāxùn·Yīncí). However, it is hard to observe and discover the points of dialect contact and merger. In the history of dialect studies, it was too early to study the differences between dialects, while it was quite late to study language contact. Although we can see dialects in the commentaries on the Confucian Classics since the Han Dynasty becoming the common language or one dialect changing to another, the records are not monographs.