"She is a northerner."
This is obviously a very mainland thing. Us nth generation hua qiao won't understand this. What's the mental map associated with coming from a region? I know there are food differences.
Being a northerner indicates certain accent/dialect traits, and probably food preferences. I would not be surprised to learn other cultural differences as well, as there are regional differences between parts of the US (the South vs. New York vs. the Midwest vs. the West Coast…)