Explanation:
Fred Donner wrote: “A few tribesmen may have wanted to migrate in order to settle on rich new lands, but as we have seen, there is little to suggest that this was a major cause of the migrations, as most emigrant tribesmen preferred to remain clustered in their new garrison towns or in the quarters of established towns that they came to occupy. Nor is the migration to be explained as the result of some natural crisis -- hunger, overpopulation, or the desiccation of pasturelands -- that forced the tribesmen out of the peninsula; 'Umar is said to have complained that he had difficulty locating enough men to conscript into the armies during the third phase of the conquests, which suggests that overpopulation was hardly a problem in the peninsula. How, after all, could any significant "surplus" population have managed to survive in an area of such precarious agricultural resources as were possessed by Arabia? The theories relating an Arab migration to long or short-term desiccation of the peninsula rest on evidence that is tenuous at best, and do not explain why the conquest and migration occurred as a sudden burst of expansive energy rather than as the gradual efflux of the most miserable in Arabian society. [Source: Fred Donner, “The Early Islamic Conquests," Princeton University Press, 1981, beginning with pg. 251. Donner is a scholar of Islam and Professor of Near Eastern History at the University of Chicago *=*]
