Late in the twelfth century the people began to move and the population began to diminish. Some of the people left the area, drifting off to the south. The rest began to search for defensive locations for their villages. In the Mesa Verde the villages were moved to the caves of which there were many hundreds in the numerous canyons. By the early part of the thirteenth century most of the Indians had moved to the caves and during the last few generations the people were in the Mesa Verde it appears that few lived in the open. There can be little doubt that the movement to the caves was caused by the arrival of an enemy group. In many parts of the Southwest, the same thing happened. Evidently some nomadic group, perhaps the earliest of the Apaches, came into the area and began to harass the Pueblo Indians. In the interest of health the peaceful farmers began to build their homes where they could defend them against marauders. After living in the open for many centuries the Pueblo Indians of the Mesa Verde moved to the caves and constructed the cliff dwellings. There can be little doubt that this move was prompted by a desire for defensive locations. [Illustration: Double House, part of which is shown here, is an excellent indication of the Pueblo Indians’ desire to utilize the caves. The ruin is in seven sections, not all of which are shown, and indicates a desire to build in easily defensible places, no matter how small or difficult of access they were. All together, Double House has about seventy rooms, with several kivas along the base of the cliff.] DEFENSIVE LOCATIONS The majority of the cliff dwellings are in locations more or less like those shown below. Villages like these could easily have been defended against raiders armed with bows and arrows. THE DEFENSIVE QUALITIES OF THE CLIFF DWELLINGS From a modern viewpoint a cave might not appear to be a safe place for a home. All thought of modern warfare must be forgotten, however, and ancient methods must be kept in mind. When it is considered that the cliff dwellers lived in bow and arrow times it is not difficult to see the cliff dwellings as defensive structures. Because of the location and the type of construction, they served as excellent forts against bow and arrow attack.