basically it is a loaded question because people don't come from land, they come from people who move around.  so if you say spanish 1000 ad vs spanish 2000 bc it's a different situation.  when you think of a north african, you're thinking of someone who has been recieving the spanish genome so maybe you are just incorrectly associating those features with africa when it actually came from spain.  'arab' just means mixed (mixed with what?). and yea it is just a reality that populations are like fluid and the closer you get to the border, the more mixing you get with other populations.  everything is a matter of degrees and it depends what level of drift you are comfortable with.
United States