We are told by the historians of the colonial period that the mining operations of the first Spanish settlers were fatal to at least a million Indians. It is quite probable that the introduction of ordinary European contagious diseases, such as measles, chicken pox, and smallpox, may have had a great deal to do with the destruction of a large proportion of those unfortunates whose untimely deaths were attributed by historians to the very cruel practices of the early Spanish miners and treasure seekers. Both causes undoubtedly contributed to the result. There seems to be no question that the population diminished enormously in early colonial days. If this is true, the remaining population would naturally have sought regions where the conditions of existence and human intercourse were less severe and rigorous than in the valleys of Uiticos and Uilcapampa. The students and travelers of the late nineteenth and early twentieth centuries, including such a careful observer as Bandelier, are of the opinion that the present-day population in the Andes of Peru and Bolivia is about as great as that at the time of the Conquest. In other words, with the decay of early colonial mining and the consequent disappearance of bad living conditions and forced labor at the mines, also with the rise of partial immunity to European diseases, and the more comfortable conditions of existence which have followed the coming of Peruvian independence, it is reasonable to suppose that the number of highland Indians has increased. With this increase has come a consequent crowding in certain localities. There would be a natural tendency to seek less crowded regions, even at the expense of using difficult mountain trails. This would lead to their occupying as remote and inaccessible a region as the ancient province of Uilcapampa. It is probable that after the gold mines ceased to pay, and before the demand for rubber caused the San Miguel Valley to be appropriated by the white man, there was a period of nearly three hundred years when no one of education or of intelligence superior to the ordinary Indian shepherd lived anywhere near Pucyura or Lucma. The adobe houses of these modern villages look fairly modern. They may have been built in the nineteenth century. Such a theory would account for the very small amount of information prevailing in Peru regarding the region where we had been privileged to find so many ruins. This ignorance led the Peruvian geographers Raimondi and Paz Soldan to conclude that Choqquequirau, the only ruins reported between the Apurimac and the Urubamba, must have been the capital of the Incas who took refuge there. It also makes it seem more reasonable that the existence of Rosaspata and ñusta Isppana should not have been known to Peruvian geographers and historians, or even to the government officials who lived in the adjacent villages.