Now the region under consideration embraces all of New Mexico and Arizona, southwestern Colorado and southeastern Utah, and is comprised within four principal drainage areas, viz: the Rio Grande, the San Juan, the Little Colorado, and the Gila, the last three being tributary to the Colorado. Over this area physiographic conditions are quite uniform and the indigenous tribes now inhabiting it likewise; not as to linguistic stock, but in general and specific culture. By indigines I mean the various sedentary tribes generally called Pueblos as distinguished from the intrusive Utes, Navajos and Apaches, which tribes cames in chiefly for predatory reasons after the indigenous tribes had acquired sufficient property to make them desirable prey. This indigenous culture was doubtless composite as to blood and the uniformity developed was the natural result of living for a long period of time under definite uniform environmental conditions. Its primary migration movement was from south to north, but branching in all directions, and the almost countless prehistoric ruins following the water-courses of the southwest are the remains of these early migrations. The present sedentary Indians of the southwest, called by us Pueblos, are thus the true indigines of that arid region so far as we can judge from existing evidences. All presumption of earlier or different races is purely hypothetical, as yet unsupported by any shadow of evidence. These primitive agriculturists became builders of more or less permanent houses, dependent always upon the permanence of the water supply. The character of their habitations was usually determined by geological environment. The characteristic style of architecture evolved was the multiple-chambered stone structure that we call the _pueblo_. The earliest of these were comparatively small, single-storied dwellings of an indefinite number of rooms rarely exceeding fifty, scattered about over the arable areas. The ruins of these to be found in the southwest are quite uncountable. Later, as predatory neighbors multiplied and the people crowded together for mutual aid the enormous hives of hundreds of cells came into existence. These were often carried to a height of five or six stories. At the same time and for the same reason another style of habitation came into existence, namely, the cliff-dwelling. Its type was always determined by geological conditions. If ledges difficult of access and protected by overhanging cliffs could be found, dwellings were built upon them, not differing structurally from pueblos. If the cliffs presented only perpendicular faces, and were of comparatively soft material, dwellings were excavated in them, single or multiple-chambered, and thus strongly defensive homes established.