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When, and how, did Mandarin become the dominant lingua franca within China? What common languages were used before Mandarin's rise?
by
Hamth3Gr3at
EnclavedMicrostate
While more might be said, a few past answers by /u/keyilan discuss various aspects of your question:
How far can I go back in time in China with modern Mandarin and still communicate with people in court?
When did Mandarin form as a recognizable language?
What was widely spoken in China before Mandarin Chinese was standardized?