The center of distribution of the tribes of this family is generally
considered to be the lower Colorado and Gila Valleys. At least this is
the region where they attained their highest physical and mental
development. With the exception of certain small areas possessed by
Shoshonean tribes, Indians of Yuman stock occupied the Colorado River
from its mouth as far up as Cataract Creek where dwell the Havasupai.
Upon the Gila and its tributaries they extended as far east as the Tonto
Basin. From this center they extended west to the Pacific and on the
south throughout the peninsula of Lower California. The mission of San
Luis Rey in California was, when established, in Yuman territory, and
marks the northern limit of the family. More recently and at the present
time this locality is in possession of Shoshonean tribes.
The island of Angel de la Guardia and Tiburon Island were occupied by
tribes of the Yuman family, as also was a small section of Mexico lying
on the gulf to the north of Guaymas.