The Chaco agricultural fields couldn't have supported their population so there was a distinct need to import food. The need to import food and raw materials is one of the evolutionary steps toward a truly urban culture. The San Juan Anasazi developed distinctive, large cliff villages, such as those at Mesa Verde National Park, toward the end of the Pueblo III period, just before the region was abandoned. The Mesa Verdeans also built towers and tower kivas. Hovenweep in Southeastern Utah has a dramatic tower, Square Tower, located near a spring.
Some sites have subterranean kivas attached to towers via a tunnel.
Some writers suggest that differences in architecture and ceramics may reflect a different language than that of the Kayenta and Chaco groups. It also had a well-designed reservoir with a dam and spillway to control the water level. At the end of the Pueblo III period, the San Juan people moved from open mesa tops, such as at Yellow Jacket, to sandstone cliff alcoves, such as Mummy House, Cliff Palace, Spruce Tree House and the others at Mesa Verde, perhaps for defense or to farm the canyon bottoms. The Kayenta Anasazi are known for their fine ceramic wares. Their homes and villages were less well built and organized than the other groups.