What is the ridiculous part? It is desert. It won't sustain large amounts of any living thing. The water they use is fossil ground water and is bound to end. The farm land suffers from salinization, that actually destroyed one of the earliest human settlements around that area (and in human history altogether).
"So how did Fertile Crescent peoples lose that big lead? The short answer is ecological suicide: They inadvertently destroyed the environmental resources on which their society depended. Just as the region's rise wasn't due to any special virtue of its people, its fall wasn't due to any special blindness on their part. Instead, they had the misfortune to be living in an extremely fragile environment, which, because of its low rainfall, was particularly susceptible to deforestation.
When you clear a forest in a high-rainfall tropical area, new trees grow up to a height of 15 feet within a year; in a dry area like the Fertile Crescent, regeneration is much slower. And when you add to the equation grazing by sheep and goats, new trees stand little chance. Deforestation led to soil erosion, and irrigation agriculture led to salinization, both by releasing salt buried deep in the ground and by adding salt through irrigation water. After centuries of degradation, areas of Iraq that formerly supported productive irrigation agriculture are today salt pans where nothing grows."
"Iraq's decline holds a broader significance. Many other countries today face similar crippling environmental problems, including the deforestation, overgrazing, erosion and salinization that brought down the Fertile Crescent. Other countries already crippled or nearly so by such problems include Haiti, Somalia, Rwanda, Afghanistan, Pakistan, Nepal, the Philippines and Indonesia."
The Erosion of Civilization - latimes