The other day, reading about modern turmoil in Lybia, I learned something exciting about an ancient civilization that bloomed there once, and decided it would be of interest to other permies.
In prehistoric times, Sahara was a much wetter and more fertile place; since those times, there remained underground reservoirs of water. Garamants (the name is Greek, we don't know what they called themselves) used this dug out water, using elaborate underground irrigation channels, to grow crops, and did that for about thousand years. As the article says,
After extracting at least 30 billion gallons of water over some 600 years, the fourth-century A.D. Garamantes discovered that the water was literally running out.
As a result, civilization sharply declined, and Arab invasion that happened soon after that swiped out the last remains. Alphabet, however, seems to have survived to this day as [wikipedia]Tifinagh[/wikipedia].
I find it especially fascinating that they discovered an abundant, yet nonrenewable resource, and were masterfully using it for generations upon generations... until it was used up.