>>13749527>The Garamantes were probably present as a tribe in the Fezzan by 1000 BC. They appear in the written record for the first time in the 5th century BC: according to Herodotus, they were "a very great nation" who herded cattle, farmed dates, and hunted the Ethiopian cave-dwellers who lived in the desert, from four-horse chariots.The description implies a vast trade; the herds of cattle were very large. For a nation spanning 70,000 sq.mi., these were probably settlements in between large expanses of only marginal land. As the herds were moved across, they probably ate everything in sight, and trampled what was left.
Desert/arid biomes are particularly sensitive, with lack of water meaning vegetative growth is slower. For the area to have supported all this husbandry, it would have had to have "banked" quite a bit carbon over the eons, just to get to that point, but once established, proved vulnerable.
This is the case today, where you see, for example, in irrigated dry land farming, erosion results in great clouds of dust which is the topsoil having lost its binding properties (humus) and being blown away bit by bit (also commingled with pesticide and fertilizer residues making it particularly toxic mixture to breathe.)
The "tragedy of the commons" type of devolution probably occurred with the occupying culture quickly draining what fossil water reserves existed (recharged over millions of years) and whatever browse was available for the animals (removing binding substrate for soils) leading to rapid acceleration of erosion, and desertification on the way to a ruinous state of complete collapse of the society.
