There's not really evidence. A grave that's unusual is in a site where there's a local legend.....that means nothing. England, Wales, and Scotland all have a few local legends that make Arthur theirs, both burials and births.
This has been a regular thing for a few years now. From the Amazon to Mexico, we now know that these societies were massive and some of them at least 10,000 years older than the Mesoamerican tribes we credit for everything.
The Mayans though, look at them blaming climate change. Something we know for a fact about the Mayans is that they had a mass deforestation issue. They plastered their houses, temples, even the roads and courtyards. It made them shiny and fancy. The problem? The plaster was made from ash. How many trees do you think you have to burn to have enough plaster to cover just 1 of those large temples? That's been verified by the age of the trees around these newfound cities. They were abandoned because they destroyed their environment for vanity.
That would be a new one for me, the salt. I'd have to assume that was a culture who tried to use seawater to make fertile land? There were varying farming techniques and mistakes. A much older civilization in Peru wiped themselves out by clearing and farming land that created massive instability in the hills around them. What happens when you remove all the trees and deep roots on hills? Erosion, baby. A heavy period of rain, mudslides and flooding, buried a large, productive society due to their own farming practices.Maybe I'm mixing up my ancient cultures, but didn't one of them collapse due to bad farming practices? I'm forgetting the details but there was something about making the soil too salty.
Oh, the Sumerians, they may have (it's a theory that's virtually never talked about). I was only thinking about Mesoamerica.I must be mixed up. I can find some articles about salinity causing the farmland in ancient Mesopotamia to become un-farmable and one tribe in Arizona that fucked up and used water from the Salt River to irrigate its crops but nothing about South America.