Which Indigenous lands are you on? Happy (?) Indigenous Peoples' Day 2022?

We are in the traditional territories of the Blackfoot Confederacy, including the Siksika, Piikani and Kainai Nations; the Stoney-Nakoda, including the Chiniki, Bearspaw and Wesley Nations; and the Tsuut’ina Nation. Southern Alberta is also home to the Métis Nation of Alberta, Region 3.

Fort Calgary is located where the Bow River meets the Elbow River. This site has long been called Mohkinsstsis by the Blackfoot, also Wîchîspa by the Nakoda, Guts’ists’i by Tsuut’ina, and it is the birthplace of the city of Calgary - part of Treaty 7.

"The People of the Dawn" – the tribes of the Wabanaki Alliance – Miꞌkmaq, Maliseet, Peskotomahkati and Penobscot

Gwent, which the Romans called Gewisse, and the Saxons called Wessex.

Bructeri, who were "absorbed" by Frankish and Saxon tribes in the early medieval period. (My family name is Saxon.)

I live in a town that is 30% Native American - predominately Navajo. There are Anasazi dwellings (abandoned) within 20 miles in two directions.

I got Canarsie (which I was unaware was a native tribe and not just a neighborhood in Brooklyn) and Munsee Lenape.

When I drove with dys in the Four Corners region, he gave me a lot of information, which then piqued my interest: I spent the later years (and on later visits) studying Puebloan history a little more intensively.

So what was your conclusion (if you have one) as to why they abandoned their rock dwellings? Was it a catastrophic event that drove them away? Drought? Did they get absorbed by or join with another peoples? Loss of food resources?

Just speculating here. Having no written records is like a vet asking a dog what's the matter.

I think that these dwellings were not abandoned suddenly but over a longer period of time, and that various reasons such as diseases, environmental influences or similar have led to this. Until "the last one turned off the light".

It is always difficult and purely speculative when there are little or no sources to explain the disappearance.

Insert "It's Aliens" meme here.

I believe drought is the most common theory. In an area with less than 10 inches of rainfall, the loss of one inch is a catastrophe. Still, our Samon Ruins is within 100 yards or so from the San Juan River.

I live a few feet away from what once was a creek that flowed, another 300 feet away, into a river. A couple miles later, the river flowed into the great Texcoco lake. Between the river and the lake, 504 years ago, you could see corn, flowers and amaranth being cultivated in the floating gardens of Tenochtitlan, capital of the cruel and powerful Aztec Empire, a city of over 250 000 people.
500 years ago, you could walk from where I live to a destroyed city, and an Aztec poet would tell you: “Our inheritance is a web of holes”.