Personally I think in the map, it shows clearly how close it is to the west border, right? Maybe different style guide? Sending this also for your reference https://en.wikipedia.org/wiki/Southwest_China …https://twitter.com/kchangnyt/status/1071161761192136705 …
The Wikipedia entry on South/southern China gives ambiguous boundaries. Shouldn't Southwest China be a subset of southern China? Why no southeastern China? https://en.wikipedia.org/wiki/South_China …