Peter Beaumont “Fall of Gaddafi opens a new era for the Sahara's lost civilisation” http://www.guardian.co.uk/world/2011/nov/05/gaddafi-sahara-lost-civilisation-garamantes
It has been prompted by new research – including through the use of satellite imaging – which suggests that the Garamantes built more extensively and spread their culture more widely than previously thought.
The research has confirmed the view of Herodotus*3 –not always the most reliable of chroniclers of his world, often supplying a good yarn when hard facts were hard to come by – that the Garmantes were a "very great nation".
Inhabiting an area around the busiest of the ancient trans-Saharan crossroads, the Garamantes were settled around three parallel areas of oases known today as the Wadi al-Ajal, the Wadi ash-Shati and the Zuwila-Murzuq-Burjuj depression with its capital at Jarmah.
They were tenacious builders of underground tunnels like Gaddafi. But while Gaddafi dug down to build huge complex bunkers, the Garamantes mined fossil water with which to irrigate their crops.
The Garamantes relied heavily on labour from sub-Saharan Africa, in the shape of slaves, to underpin their civilisation. Indeed, it is believed that they traded slaves as a commodity in exchange for the luxury goods that they imported in return.
Occupying an area of some 250,000 square miles, the Garamantes, whom Herodotus described colourfully as herding cattle that "grazed backwards" and hunting Ethiopians from their chariots, are now known to have practised a sophisticated form of agriculture, occupying villages set around square forts or qasrs.
The very existence of the desert culture, however, was based on their use of underground water extraction tunnels – known as foggara in Berber, one of the peoples from whom the Garamantes were descended – whose construction was highly labour-intensive, requiring the acquisition of large numbers of slaves.
The Garamantian civilisation was unique. Its foundation is believed to have marked the first time in history when a riverless area of a major desert was settled by a complex urban society which planned its towns and imported luxury goods.
Indeed the sophistication of Garamantian building design – not least of its fortifications – may have been copied by the Romans, some of whose forts in north Africa are strikingly similar in appearance.
So what happened to the Garamantes? In the end, like the Easter Islanders, the Anasazi, the Greenland Norse and the Maya – all civilisations whose downfall was studied by Jared Diamond in his book Collapse – it appears the Garamantes outgrew their ability to exploit the environment around them.
In the six centuries that they thrived, the Garamantes extracted, it is estimated, in the region of 30 billion gallons of water through the foggara system of subterranean tunnels.
In about the fourth century, however, the water started to run out, and to have dug deeper and further in search of it required more slaves than the Garamantes' military power could successfully deliver.
They reached what might be called a "peak water" moment. When they had passed peak water, the Garamantes – the "very great nation" ― were doomed to decline.
Jona Lendering “Garamantes” http://www.livius.org/ga-gh/garamantes/garamantes.html