A peculiarly interesting class of ruins is that of the pueblo villages that were occupied at the time of the coming of the Spaniards and abandoned during the next century. Archæological work in such sites should yield valuable results by disclosing the first influences of the exotic civilization upon the indigenous tribes. Noteworthy sites of this character are those near Zuñi and a number of the Rio Grande Valley. The Southwest is rich in historic sites, but in prehistoric remains its wealth is practically limitless. It is with these that we shall deal principally in this paper. The distribution of the indigenous tribes of America was determined primarily by drainage; that is to say, the food quest was the chief concern of primitive man. First of all, he sought food and water, and we can readily see that, of these two, water was first in importance. Where water was, there food was likely to be. Game frequented water courses. Plant food depended upon moisture. Now in the southwest, water was scarce, consequently no other portion of the United States was so poor in game. Hunting tribes, therefore, shunned its desert wastes. Their frontiers were the Pecos valley in eastern New Mexico, practically the western limit of the buffalo, and the divide running east and west across southern Colorado and Utah, separating the San Juan, south of which lay the arid region, from the splendid hunting ranges on the north which extended from ocean to ocean except where broken by the Utah and Nevada deserts. There was thus a tract of country bounded on the east by the Pecos river, on the north by the San Juan, extending west to the Colorado and south to the Gila in which aridity was the dominant climatic condition. Being poor in game, it was not until comparatively recent times that it was much frequented by nomadic Indians. Comanches, Utes, Navajos and Apaches had no use for this region until it was occupied by some one whom they could dispossess of wealth. Primitive economic systems are not unlike those of civilized men. In both states of culture, wealth is acquired in two ways, namely, by producing it and by dispossessing others of it. Savages and civilians naturally divide into two great classes, the productive and the predatory. It is a far cry from the murderously straightforward method of the Apache to the highly specialized up-to-date commercial system, or even the comparatively direct methods of modern politics, but the difference is merely in technique. Now in the absence of game and of victims for robbery, the first settlers of that arid region were driven to produce their living by agriculture. This could only be successfully done by irrigation. Accordingly lines of migration followed water ways and springs. Moreover, this condition was conducive to a comparatively sedentary life, and this leads to permanent home building.