Ancestral Pueblo culture reached its height between about 900 and 1150, during an unusually wet period in the Southwest. In Chaco Canyon, a cluster of twelve large towns forged a powerful confederation numbering about fifteen thousand people. A system of roads extended from the canyon to satellite towns as far as sixty-five miles away. The roads were perfectly straight; their builders even carved out stairs or footholds on steep cliffs rather than go around them. By controlling rainwater runoff through small dams and terraces, the towns fed themselves as well as the satellites.
