barbarism when first discovered by the invading European. All the
Indians of North America were in this state of transition, but the
pueblo tribes had more nearly reached the higher goal.

The great number of ruins found throughout the land has often been
interpreted as evidence of a much larger pueblo population than has been
found in post-Columbian time. But a careful study of the facts does not
warrant this conclusion. It would seem that for various reasons tribes
abandoned old pueblos and built new, thus changing their permanent
residence from time to time; but more frequent changes were made in
their rancherias. These were but ephemeral, being moved from place to
place by the varying conditions of water supply. Most of the streams of
the arid land are not perennial, but very many of the smaller streams of
the pueblo region discharge their waters into the larger streams in
times of great flood. Such floods occur now here, now there, and at
varying periods, sometimes fifty years apart. When dry years follow one
another for a long series, the channels of these intermittent streams
are choked with sand until the streams are buried and lost. Under such
circumstances the rancherias were moved from dead stream to living
stream. In rare instances pueblos themselves were removed for this
cause. Other pueblos, and the rancherias generally, were abandoned in
time of war; this seems to have been a potent cause for moving. When
pestilence attacked a pueblo the people would sometimes leave in a body
and never return. The cliff pueblos and dwellings, the cavate dwellings,
and the cinder-cone towns were all built and occupied for defensive
purposes when powerful enemies threatened. The history of some of the
old ruins has been obtained and we know the existing tribes who once
occupied them; others still remain enshrouded in obscurity.