The h > sh shift from ancient Chinese to modern Mandarin

When the Ming empire collapsed, the Guanhua (Chinese koine) at the time was based on the Nanjing accent, and that was evident in Matteo Ricci, Ferdinand Verbiest and Johann Adam Schall von Bell’s records.

The current form of Mandarin wasn’t widely used in Beijing’s outer city even by 1815 when Robert Morrison wrote his Chinese dictionary.

So the current form of Mandarin probably didn’t gain its current status until the 1850s. Based on that, the current form of Mandarin is probably at most 200 years old, and grew out of the Manchu-Old Pekingese pidgin adopted by the Manchus living in the Inner city.

I wrote a much more detailed post on this subject here: