Although degeneration in arts is common enough, a peculiar condition prevailed in the pueblo region. So far as the architecture was concerned war and a hostile human environment produced not degeneration but development. This came about partly by reason of the peculiarities of the country, and partly through the methods of war. The term war is rather a misnomer in this connection, as it does not express the idea. The result was not brought about by armed bodies of men animated by hostile intentions or bent on extermination, although forays of this kind are too common in later pueblo history, but rather by predatory bands, bent on robbery and not indisposed to incidental killing. The pueblos, with their fixed habitations and their stores of food, were the natural prey of such bands, and they suffered, just as did, at a later period, the Mexican settlements on the Rio Grande, with their immense, flocks of sheep. It was constant annoyance and danger, rather than war and pitched battles.

The pueblo country is exceptionally rich in building material suited to the knowledge and capacity of the pueblo builders. Had suitable material been less abundant, military knowledge would have developed and defensive structures would have been erected; but as such material could be obtained everywhere, and there was no lack of sites, almost if not quite equal to those occupied at any given time, the easiest and most natural thing to do was to move. Owing to the nature of the hostile pressure, such movements were generally gradual, not en masse; although there is no doubt that movements of the latter kind have sometimes taken place.

These conclusions are not based on a study of the ruins in Canyon de Chelly alone, which illustrate only one phase of the subject, but of all the pueblo remains, or rather of the remains so far as they are now known. They imply a rather sparsely settled country, occupied by a comparatively small number of tribes and subtribes, moving from place to place under the influence of various motives, some of which we know, others we can only surmise. It was a slow but practically constant migratory movement with no definite end or direction in view. The course of this movement in a geographical way does not as yet reveal a preponderance in any one direction; tribes and subtribes moved from east to west and from west to east, from north to south and from south to north, and many were irregular in their course, but the movements, so far as they can now be discerned, were all within a circumscribed area.

There is no evidence of any movement from without into the pueblo group, unless the close relation of the Hopi (Moki) language to the other Shoshonean dialects be such evidence, and none of a movement from within this area out of it, although such movements must have taken place, at least in the early history of the region. It must be borne in mind in this discussion that while we can assign approximate boundaries to the ancient pueblo region on the north, east, and west, no limit can as yet be fixed on the south. The arid country southward of Gila river and northward of the Mexican boundary would be a great

obstacle to a movement either north or south, but little as we know about that region we do know that it was not an insurmountable obstacle. The Casas Grandes of Janos, in Chihuahua, closely resemble the type of ruins on the Gila river, in Arizona, of which the best example we now have is the well-known Casa Grande ruin. We know that there are cliff ruins in the Sierra Madre, but beyond this we know little. Concerning the immense region which stretches from Gila river to the valley of Mexico, over 1300 miles in length, we know practically nothing.

In that portion of the pueblo region lying within the United States migratory movements have, as a rule, been confined to very small areas, each linguistic family moving within its own circumscribed region. Some instances of movement away from the home region have taken place even in historic times, as, for example, the migration of a considerable band of Tewas from the Rio Grande to Tusayan, where they now are, and moreover, this movement probably occurred en masse and over a considerable distance; but there is little doubt that the usual procedure was different.

Canyon de Chelly was occupied because it was the best place in that vicinity for the practice of horticulture. The cliff ruins there grew out of the natural conditions, as they have in other places. It is not meant that a type of house structure developed here and was transferred subsequently to other places. When the geological and topographical environment favored their construction, cliff outlooks were built; from a different geological structure in certain regions cavate lodges resulted; in other places there were "watch towers;" in still others single rooms were built, either lone or in clusters, and these results obtained quite as often if not oftener within the historic period as in prehistoric times.

Notwithstanding the possible division of the De Chelly ruins into four well defined types, there is no warrant for the assumption of a large population. The types are interrelated and to a large extent were inhabited not contemporaneously but conjointly. There are about 140 ruins in Canyon de Chelly and its branches, but few of them could accommodate more than a very small population. Settlements large enough to furnish homes for 50 or 60 people were rare. As not all of the sites were occupied at one time, the maximum population of the canyon could hardly have exceeded 400; it is more likely to have been 300.

The character of the site occupied is one of the most important elements to be studied in the examination of ruins in the pueblo country. In De Chelly whatever defensive value the settlements had was due to the character of the sites selected. It is believed, however, that other considerations dictated the selection of the sites, and that the defensive motive, if present at all, exercised very little influence in this region. The sites here are always selected with a view to an outlook over some adjacent area of cultivable land, and the structures erected on them were industrial or horticultural, rather than military or defensive.