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>> “Islam’s fault. And what I wrote is history. Not a joking matter.” <<
Islam was born long after the desert (7th century)
But I agree with much of your premise. The people that later became Islam did create part of the problem.
The rest was the unavoidable consequence of the Genesis 6 judgment.
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Up until the Muslims swept through North Africa, the area from Egypt to Mauritania fed the ancient world from it huge grain and animal farms. After the invasion, there was hardly any vegetation and the area turned into a semi-arid desert - then the Sahara began to creep northward.