[I'll try not to make this post too long, but no guarantees...]
Most Americans know little about "Anasazis" -- the Old Ones who lived in and beyond the Four Corners region of Utah, Colorado, New Mexico and Arizona. ("Anasazi" is a Navajo pejorative meaning "Ancient Enemies." It's rarely used among modern Pueblo peoples.)
It may or may not be widely known that the Pueblo peoples of New Mexico and Arizona are the living descendants of the Old Ones who built the magnificent ruins in Chaco Canyon and elsewhere in the region, but for the most part, these descendants are reluctant to speak with Anglos and their archaeologists and anthropologists about what they know regarding the Old Ones and ancient times. Consequently, a lot of mythology has been built up to explain the ruins and the people who built and then abandoned them.
One of the chief myths is that the "Anasazis disappeared." They didn't. Their descendants are alive today; they have been around throughout historical times; they have had much contact with the scholars and experts who came to study the ruins; and they have had very little to say about it.
On the other hand, Navajos, who are not the descendants of the Old Ones but who arrived in the Four Corners region in the period between 1400 and 1500, long after the buildings in Chaco Canyon and elsewhere in the region had largely fallen to ruin, have and tell lots of stories about them.
Consequently, much of what the Navajos have to say about the Old Ones is pure invention, some of which is clearly designed to please the scholars and confirm their biases -- though seemingly, it doesn't occur to the scholars that that could be so. Indians, like children, never lie, right?
As I've written about in the past, Ms Ché and I have been to Chaco Canyon a number of times (she more than me), and we've explored and gotten a pretty good sense of the place and what it was to the Old Ones -- and to some extent why it was allowed to fall into ruin.
The Chacoan world was extensive -- reaching far beyond Chaco Canyon -- and it was never completely abandoned. Still today, Pueblo peoples visit and perform ceremonies at any number of ancient sites throughout the region, and those areas that could support a Native variety of agricultural living have done so for untold ages. In effect, the "Anasazi" not only didn't disappear, some of them never left.
But there were hard times, very hard times in the region. Keeping going what had been created in the Four Corners during the relatively brief florescence of the "Chaco Phenomenon" didn't make a whole lot of sense, and rather continue what didn't work under the circumstances, most of the people moved away and only returned as (sort of ) pilgrims.
The circumstances were lengthy droughts that made farming almost impossible throughout much of the Southwest.
The Chaco Phenomenon depended on extensive and productive farming activities; when that was impossible due to lack of water and other resources, it was time to give up the phenomenon of spectacular building in relatively remote locations.
And so the Old Ones did. They moved away to relatively well watered areas (such as the Rio Grande valley) and gave up the spectacles of the Great Houses that have captivated scholars and others for many a long year.
Great Houses were not living quarters for the most part, nor was the bulk of these buildings used for storage when they were at their height. In fact, most of the ground floor rooms were empty when they were excavated. Many showed no signs of ever having been used for any purpose while others appeared to have once been used -- either for storage or living quarters -- long ago but hadn't been used for many years before the collapse. That's because they weren't "rooms" in the sense that most of us would understand the term. They were either built for or ultimately became foundations for upper stories. Much of these upper stories, in turn, became foundations for higher stories yet.
The Great Houses were essentially trading and ceremonial/celebratory centers. Something like pow-wow/trading posts.
They depended on farmers, craftspeople and artists to produce surpluses for trade, and on a wide variety of people to come to the Great Houses to exchange their goods for those available (often only available) at the Great Houses and to engage in their gathering together and ceremonial practices at the Great Houses.
When the droughts came and persisted, there was no surplus any more; there was great want instead. For a while, the Great Houses had enough supplies on hand to alleviate some of that want, but eventually their supplies were exhausted, and when that happened, there was no longer sufficient reason to regard the Great Houses as "centers" and they were largely allowed to fall to ruin.
Navajos say the ruins are filled with malevolent spirits, but the Pueblo peoples appear to disagree. Instead, they see the ruins as ... well, ruins. What used to be but isn't any more. Filled with neither "good" nor "bad" spirits but largely empty now because they are not necessary for the living. And if the scholars would leave them alone (but of course they won't) these places would be the peaceful resting places for Pueblo ancestors.
Unfortunately, the scholars have an urge to dig, dig, dig, and they recruit the nearby Navajos to assist.
To the Navajos, the whole "Chaco" thing is kind of creepy, understandably so from their point of view.
Because the scholars essentially can't find out from the Pueblo descendants of the Chacoans about how the Chacoan society worked in ancient times (they're not tellin') they have had to speculate given the physical evidence they find and the stories they've been told by those who will talk (primarily Navajos.)
Their speculations tend to find parallels between the Old Ones and whatever contemporary phenomena in "modern" society suits their fancy.
For example, the Great Houses were once considered by scholars to be vast apartment houses much like -- but larger than -- those being built in big cities at the time. Only they weren't. They may have been begun as living-quarter/storage compounds, but they fairly quickly became something else again, as their trade and ceremonial aspects came to the fore. Once their purpose was revised and their expansion was under way, they were never used primarily as living quarters again.
But for decades, scholars clung to the notion that they were apartment houses much like those being built in big cities.
They were more like shopping malls and theme parks, but that's not an accurate assessment, either, as I suspect the Old Ones didn't have those concepts in their own time.
The popular scholarly notions now focus on the collapse of the Anasazi Ways, in parallel with their anticipation of the collapse of Western Civilization due to climate change and over-exploitation of resources. What happened at Chaco and elsewhere in the Anasazi world is seen as a warning to the rest of us of what could happen if we go too far.
This is not unlike the theories of what happened at Rapa Nui when population pressure and resource depletion combined to cause chaos and devastation.
However, there doesn't appear to be evidence of chaos and conflict within Chaco Canyon itself. Instead, there is evidence of a gradual restriction of access. What had been open and relatively welcoming became constricted until ultimately there was no access to outsiders, and eventually even the "insiders" decided it was time to leave.
The idea that the Chaco Phenomenon and the Anasazi Way were the products of an elite -- perhaps from outside the region, either from Mexico or Central America -- is one of the persistent scholarly notions. This idea also parallels ideas regarding Western Civilization and its elites. The problem, as I see it, is that Native concepts of "elite" don't mirror those of the West. They are really quite different points of view, and the effort to make direct parallels is bound to fail. Particularly irksome is the notion that an elite from elsewhere would have to come to the Four Corners to show the simple Natives (a la colonialists) how to build and how to run a Great House enterprise.
As if these simple Natives couldn't figure it out for themselves.
Every indication is that there extensive trading and communications networks all over the Americas from a very early time, and signs are that the Chacoans were in regular trade contact with Mexicans and Central Americans as well as with the coastal peoples of North America. They probably had contacts well beyond any that have so far been recognized by scholars.
There is a tendency for scholars to consider each Native American group as an isolate, unconnected with other groups, particularly at any distance, but the evidence suggests there were highly developed intertribal trade and communications systems all over the Americas prior to the arrival of Europeans. The notion that the Chacoans, for example, were some kind of isolated tribe who couldn't have done what they did without the intervention of a more advanced "elite" from elsewhere is nonsense. But it does fit the colonialist mindset almost perfectly.
What caused the collapse of the Chacoan system? It seems obvious enough, given what the system had originally been established to do: provide a "center" for surplus storage, trade, ceremonies and gatherings.
The system was given up when it was no longer possible to maintain it because of persistent and repeated droughts.
When the Chacoan system could not function -- due to lack of surplus production largely due to droughts -- the people didn't need or use it any more. They found alternatives that suited their needs better. One of the alternatives was the dispersal of "center places" and the disinclination to repeat the Chacoan pattern of vast Great Houses to serve as centers for surplus accumulation and trade.
Yet people from all over the region and beyond continued to visit Chaco Canyon and associated sites after they were largely abandoned and fell to ruin. The ceremonial aspects of these places seem to have endured through all sorts of adversity and over many centuries. Some of these ceremonies are still celebrated today.
There are few signs of conflict and struggle within Chaco Canyon itself, but there seem to be quite a few signs of conflict elsewhere in the Chacoan world. No doubt, as surpluses disappeared and the Great Houses could no longer perform the function of storage/redistribution/trade, what little was left in them became prime targets for raiders looking to their own survival. Some of those raids were highly destructive, leaving many dead and destroyed structures. Some scholars have speculated that the raiders were Navajo and Apache moving into the region from the north, but others dispute this, as they can find so little evidence that the Navajo and Apache were even in the area prior to about 1400, which would be a century or more after the conflict period. No, it seems more likely that such conflict as there was involved raids by other nascent Pueblo bands, descendants of the Old Ones just like those who were being raided.
Ultimately, the smaller Chacoan outposts were destroyed or abandoned and the survivors migrated elsewhere -- places where their descendants still are.
They maintain certain aspects of the Old Ways, aspects they may or may not be willing to discuss with scholars. But they have also been willing and able to adapt to new ways both of their own invention and brought by the various waves of conquest and immigration over the centuries. Pueblo culture and society isn't static any more than Chacoan culture and society was. It is always adapting, developing its own ways, and passing on the wisdom of the Old Ones too.
The best Anglo outsiders can do is give respect to the Old Ones and their Pueblo descendants and admit that ignorance is the fundamental state of Anglo being.
We don't really know and we're not likely to know what really happened to the Old Ones, and... it doesn't really matter.
They don't have the solutions for our present predicament, any more than the Indians could have solved all the psychic problems of the invaders.