For reasons that are subject to debate, during the period of 1400 to 1500 A.D. large community centers were abandoned in the American southwest, as were many canals. The people did not die out, they moved instead to smaller villages in small groups. They spread throughout much of the Southwest, including northern Arizona. They adapted to some changed conditions in other words.

What really interests me is why this occurred. It is one of the genuine mysteries of North American archaeology. I believe it has continuing important significance for our modern societies. There are lessons for us to learn here. Will we learn them?

They may have left because of environmental collapse. For example, because the ancestral people of the Sonoran desert were so successful at farming they may have produced too many people for the land to sustain.  People around the world need to learn modesty and humility. That certainly applies to us moderns as well.

When Spanish missionaries arrived at the end of the 17^th century, they found only an empty shell of the once flourishing village of Casa Grande (as the Spanish called it). Over the next two centuries, many visitors visited the site and damaged it over and over again. Some were like vandals ruining what they saw. We could see graffiti from this time on the walls.  In the late 1800s scientists pressed for its formal protection and in 1892 Casa Grande Ruins National Monument became America’s first archaeological reserve. To this day, the Great House keeps the secrets of the Ancestral People of the Sonoran Desert within its protected walls.

We all must learn that societies collapse. Everyone has done that and so will ours.