182 INDIANS OF THE SOUTHWEST. 
issue is rather the time at which their influence was 
exerted and the type of culture on which this southern 
culture was grafted. 
We now know that the architecture of the South- 
west, the honey-comb-like community houses, often 
terraced, developed in the Southwest with little or no 
outside stimulus. The decoration of the pottery is also 
a native growth. It is possible to trace its development 
Petroglyphs. San Juan Valley. 
(Courtesy of Dr. Prudden.) 
from a beginning of crude black designs on a white back- 
ground to the highly ornamented and locally differen- 
tiated decorations of the beginning of the Spanish 
period. Much of the elaborate social, political, and 
ceremonial organizations of the present must have 
grown up with the concentration of the population into 
large community houses. 
The pueblo-dwelling peoples of the Rio Grande 
region have been subjected to constant influence from 
the tribes of the Plains. They not only received many 
articles used for food and clothing by trade with these 
