Are all people from Africa black? No, of course not. Are all people from America/Europe white? No, of course not.
So then, why do you want to define the "race" Asian using geography? When all others are based on skin-color/culture/identiy, for lack of a better way of simply-defining it.
At this point, I'm half-expecting someone to correct me about my definition/description of races. Or perhaps be told about some sort of already-formalized, government-endorsed definition of one of the races above that I got wrong.
Hmong households have slightly lower median incomes than the total US population, for instance.[0]
[0] http://www.hndinc.org/cmsAdmin/uploads/dlc/HND-Census-Report...
So does white/caucasian, and probably all the other race "colors" as well. I.e. They lump together many different geographically-isolated/defined peoples and cultures into one singular entity for simplicity. And then we're led to believe statistics that are somehow indicative of something regarding that "race".
Interestly enough, in the UK 'asian' refers strictly to people from India/Pakistan.
http://www.pewresearch.org/fact-tank/2016/05/11/the-challeng...