Under the Yuán, the Chinese language undergoes yet again several major transformations, the most notable of which is its transformation into a family of languages from a single fragmented language.
In what will become the lands where Mandarin is spoken today, late Middle Chinese evolves into Proto-Mandarin Chinese. In the southern provinces, each regional dialect becomes a language in its own right, Mǐn much more so than the other ones.
These changes are probably made more dramatic by the harsh rule of the Mongols, who divide the Chinese into two peoples, Northerners and Southerners, with different rights. Chinese culture appeals less to the (foreign) élite, and thus more popular literary forms appear, such as Chinese drama (known as "Chinese opera" in the West), which is performed in vernacular Chinese. Story-telling also becomes extremely important under the Yuán, as do novels written in báihuà 白話 ('written vernacular').
From the Yuán on, there are two concurrent ways of writing Chinese: Literary Chinese (wényán), and Written vernacular Chinese (báihuà).