Recently, some genetic studies have directly related specific languages with specific genes and ethnos. At least so far, these ideas or speculations are too optimistic and confident. After all, ethnos is only a kind of distinguishing relationship between the different ethnic groups, language is a kind of culture that could be shared by different ethnos, and genes are a kind of biological fact of race. We cannot yet now make sure if there is one-to-one correspondence between the language, genes, and the ethnos. The field experiences from Yunnan showed that an ethnic group may speak two or more languages, and two ethnic groups may not identify with each other, although they are from the same ancestor and speak the same language. Based on these facts, this paper researches some literature and some archaeological studies on the early history of Yunnan, and speculates that Chinese spread to Yunnan in the Shang dynasty, and Bai language subsequently developed from it.