Final answer:
The Anasazi built on cliff walls for protection by creating less accessible dwellings to defend against invaders and to shelter from the environment. Strategic locations like Mesa Verde offered natural defense and were well-planned to accommodate their society's needs.
Step-by-step explanation:
Building on cliff walls provided protection for the Anasazi primarily by making their dwellings less accessible to potential invaders. The Anasazi, a Native American people who lived a long time ago in the Southwestern United States, constructed more than 600 structures into the cliff faces of the Four Corners region, including what is today Mesa Verde National Park in Colorado. These structures were well-planned, with large, apartment-like buildings organized around open plazas for community gatherings.
The Anasazi became cliff dwellers as a strategic move to protect their communities from nomadic raiding groups. With homes accessible only by ladder or rope that could be withdrawn, they could effectively prevent unauthorized access. The location also provided natural defenses as well as shelter from the elements, such as offering shade and protection from snow. While the exact reasons for constructing these cliff dwellings remain a matter of speculation, there is a consensus that defense was a significant factor.
The development of these cliff dwellings represents a remarkable architectural achievement. The Ancient Puebloans utilized stone and mud mortar, along with wooden beams, to create large, multi-storied buildings that fit into the natural clefts in the cliff face. Cliff Palace, the largest cliff dwelling, has about 150 rooms and more than twenty circular rooms, highlighting the advanced building techniques and the social organization of the Anasazi people.