Source : Webster's Revised Unabridged Dictionary (1913)

Yumas \Yu"mas\, n. pl.; sing. {Yuma}. (Ethnol.)
   A tribe of Indians native of Arizona and the adjacent parts
   of Mexico and California. They are agricultural, and
   cultivate corn, wheat, barley, melons, etc.

   Note: The a wider sense, the term sometimes includes the
         Mohaves and other allied tribes.

Source : WordNet®

Yuma
     n 1: a member of the North American Indian people of Arizona and
          adjacent Mexico and California
     2: a town in southwestern Arizona on the Colorado River and the
        California border
     3: the Yuman language spoken by the Yuma people