By the late Ming Dynasty(1602), the Beijing dialect of the Chinese language had witnessed the phenomenon of palatalization in the fine sounds of jian 见 group andjing 精 group, but the two kinds of sounds, called respectivelytuan 团 sounds and jing 尖 sounds today, were still entirely different from each other. From the same period when the primary edition of Jiu Manzhou Dang 旧 满 洲 档 (Government archive of the early Manchu/Manzhou) [MG 1607-1636], we can see that the Manchus in the Northeast of China confused the two kinds of sounds at the beginning of learning Chinese language, which is described as the merge of jian andtuan sounds. After the entry of Manchus (1644), characterized by the merge of jian andtuan sounds, the imperfect Chinese language spoken by Manchus entered the inner city of Beijing and formed a contrast with the traditional Chinese language spoken by the Han people in the outer city of Beijing. Due to the implementation of the Manchu as the national language (guoyu 国 语) in the early Qing dynasty, the language spoken by Manchus in the inner city affected the language spoken by the Han people in the outer city through education. About 100 years later (1743-1810), in the spoken Chinese of the Han people in the outer city, the phenomenon of merging jian and tuan sounds appeared first only in some words, and then finally took over completely. This shows that the phenomenon of merging jian andtuan sounds in the Beijing dialect of the Qing dynasty is a result of the horizontal transmission of linguistic features from the Manchus in the inner city to the Han people in the outer city. The so-called “horizontal transmission” is the mutual effect between different languages when they contact with each other. The history of the Beijing dialect of the Qing dynasty is a history of the Manchus in the inner city abandoning the Manchu language, which was first converted imperfectly into the Chinese language and then finally merged with the spoken Chinese of the Han people in the outer city. In this process, on account of the special social status of the Manchus in the inner city, their spoken Chinese with the merge jian andtuan sounds affected that of the Han people in the outer city, and eventually prompted the same merge of two sounds of jian andtuan sounds among the latter, just as what had happened to the Manchus