South of the civilized lands of the eastern half of
Eurasia lies the
Indian Ocean, a significant commercial scene since ancient times, but
not the stuff of which conquests are made. South of the civilized lands
of the western half of Eurasia there is desert—notably the vast expanse
of the Sahara. This was unprofitable territory for agriculturalists
outside a few oases, but it did provide sufficient vegetation for a
thin and hardy population of nomadic pastoralists. One Berber people of
the western Sahara came out of the desert in the eleventh century to
conquer much of North Africa and southern Spain; but they were Muslims
like the peoples they conquered, and their impact was a transient one.
That leaves us with Arabia, essentially a fragment of the Sahara cut
off from the main body of the desert by the Red Sea. It hardly seems
worth troubling with such limited and unpromising environment. And yet
the single civilising force that did most to unify Eurasia before
modern times came out of Arabia.
