Comment: I have read

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I have read

the climate in the SW as it existed when Europeans first
settled (and which has not changed that much, at least until
fairly recently) is/was not representative of what the climate is
like there permanently.

Supposedly, they arrived during what is actually a period of
relatively abundant rainfall, but the overall conditions are usually
much drier. Within the last thousand years there is evidence of
droughts of as long as 50 years - and even longer ones within
the last 2000 years.

http://www.smithsonianmag.com/people-places/anasazi.html?c=y...

this page has a 2000+ year precipitation reconstruction for NW New Mexico:

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

Note that rainfall is unusually consistent and drought period
minimal for most of the 19th and 20 centuries compared to
the periods before that.

People who live in deserts probably ought to develop lifestyles
that take that into account...