An interesting question. If they did see blue, it is hard to imagine having
no word. If they had no word, it is hard to suppose that they saw blue.

For those interested in this question, I can recommend a book devoted to the subject (a beautiful one, too):

Blue : the history of a color / Michel Pastoureau.
Princeton : Princeton University Press, c2001.

Subject(s):    Blue.
Color--Psychological aspects--History.
Color--Social aspects--History.
Symbolism of colors--History.
Blue in art.
ISBN:    0691090505 (alk. paper)

Collection:    UCLA Libraries and Collections
------------------------------------------------------------------------
Location:    Biomed History and Special Collections Stacks
Call Number:
   BF789.C7 P2935b 2001

Carolyn