Four Corners

[uniface]

CORTEZ, COLORADO—Archaeologists are excavating a 1,500-year-old village near Mesa Verde that appears to be the first settlement in the Four Corners region to have been occupied year-round by farmers. “This is the first population to move into the central Mesa Verde region and farm and be sedentary full time,” Susan Ryan, Director of Archaeology at the Crow Canyon Archaeological Center, told Western Digs. The site features ten pithouses built in a diversity of architectural styles organized around an underground ceremonial chamber, known as a great kiva. Dating to A.D. 570, the kiva is the earliest to be found in the region. “We think we’re at the very first site that has a village forming around public architecture in the central Mesa Verde region, and that’s unique,” said Ryan. Prior to the establishment of the village, which is known as the Dillard site, the area was populated by people who were still highly mobile and alternated between foraging and farming. The kiva would have helped socially integrate people of diverse backgrounds who were transitioning into a new, fully agricultural way of life. The Dillard site heralded a revolutionary change in Southwestern prehistory, but within a hundred years of being built, its great kiva was ritually burned and abandoned.     

http://www.archaeology.org/news

[Minimalist]

I've been to Four Corners. Not a great farming area now.

[kbs2244]

Well, it must have had some attraction back then.
It seems to have been a cultural meeting place.

“The kiva would have helped socially integrate people of diverse backgrounds who were transitioning into a new, fully agricultural way of life.”

Hunters and farmers don’t typically mix very well.
One is a take and move on to the next easy kill life, while the other is a stay put in one place and tough it out life style.

[Minimalist]

Its' a complex issue but given the use of irrigation by the locals it would seem that water was a primary factor. This article speculates on some other causes but as we see in modern drought situations there is invariably social conflict as a result. These things rarely happen in a vacuum.

http://www.ncdc.noaa.gov/paleo/ctl/cliihis1000.html