This term for nobility comes from the Spanish sangre azul
... Spanish nobility used sangre azul to differentiate 
between classes of nobility descended from the Moors and those descended 
from the... [DOC] [TLE] "Blue blood" as nobility from spanish Sangre Azul - The Apricity ... [PAR] Blue blood is a well known term for royalty and nobility, but how did this word 
come about?