After a period of about forty years, during which the Christians were steadily increasing their dominions, Coria and Mora and other Mahometan strongholds were acquired by Alfonso, now styled the "Emperor"; and almost every contest between the two natural enemies had turned to the advantage of the Christians. So long, indeed, as the walis were eager only to preserve or to extend their authority, independent of each other and of every superior, this success need not surprise us--we may rather be surprised that the Mahometans were allowed to retain any footing in the Peninsula. Probably they would at this time have been driven from it but for the seasonable arrival of the victorious Almohades. Both Christians and Africans now contended for the superiority. While the troops of Alfonso reduced Baeza, and, with a Mahometan ally, even Cordova, Malaga, and Seville acknowledged Abu Amram; Calatrava and Almeria next fell to the Christian Emperor, about the same time that Lisbon and the neighboring towns received Don Enrique, the new sovereign of Portugal. Most of these conquests, however, were subsequently recovered by the Almohades. Being reinforced by a new army from Africa, the latter pursued their successes with greater vigor. They reduced Cordova, which was held by an ally of Alfonso; defeated, and forever paralyzed, the expiring efforts of the Almoravides; and proclaimed their Emperor Abdelmumen as sovereign of all Mahometan Spain. Notwithstanding the destructive wars which had prevailed for nearly a century, neither Moors nor Christians had acquired much advantage by them. From the reduction of Saragossa to the present time, the victory, indeed, had generally declared for the Christians; but their conquests, with the exception of Lisbon and a few fortresses in Central Spain, were lost almost as soon as gained; and the same fate attended the equally transient successes of the Mahometans. The reasons why the former did not permanently extend their territories, were their internal dissensions; while Leon was at war with Castile, or Castile with Leon, or either with Aragon, we need not wonder that the united Almoravides, or their successors the Almohades, should sometimes triumph; but those triumphs were sure to be followed by reverses whenever not all, but any one, of the Christian states was at liberty to assail its natural enemy. The Christians, when at peace among themselves, were always too many for their Mahometan neighbors, even when the latter were aided by the whole power of Western Africa.