The seventh century saw the ascendency of Mohammed (born A.D. 570) in Arabia, to which country his personal power, temporal and religious, was limited. Upon his death, in 632, his followers determined on the invasion of Persia and the Asiatic dominions of the Emperor at Constantinople. Mohammed's successor, Abubekr, the first of the Khaliphs (_i.e._, "representatives" of the prophet), at once waged war in both directions. Persia speedily succumbed; Syria and Palestine were subjugated after seven years by the Khaliph Omar. The reduction of Egypt followed, and during the remainder of this century the Saracens, the name by which the followers of Mohammed became termed in Christendom, extended their territory across the entire length of North Africa, and shortly afterwards even into Spain, where they overpowered the then disunited Visigoths. The Saracen power in Western Asia was distracted during the next century by civil war, and was further weakened by unsuccessful wars against the Greeks. At length, in 750, the seat of government was moved from Damascus to Bagdad. From the eighth century onward, though the religion of Mohammed gained ground, and continues to do so to-day, the empire established by his followers dwindled rapidly, one province after another shaking off its allegiance until at the end of the tenth century its shattered dominions lay open to the nearest invader. The foe appeared in the shape of the formidable Turk. Eastern Empire at End of 10th Century. In view of the entrance of this new enemy we may note the extent of the territory belonging at this time to the eastern branch of the old Roman world, the Byzantine Empire, as it is termed (from Byzantium, the ancient name of Constantinople). The Eastern Emperors had recovered some of their lost ground in Asia, and at the close of the tenth century they held all Asia Minor, Armenia, a part of Syria, a considerable portion of Italy, and all the Balkan Peninsula. The Appearance of the Turks. Beyond the north-eastern border of the Saracen dominions lay the country of Turkestan, inhabited by the Turks, a branch of the warlike nation of the Tartars of Central Asia. With them the Saracens, after the establishment of their Government at Bagdad, waged successful warfare for a time, taking numbers of Turks captive and dispersing them over the Empire. This only facilitated the eventual downfall of the Saracen sovereignty. The Turks in Western Asia grew in influence, and at length the Turkish troops, breaking into open revolt, assumed control over the Khaliphate, deposing and nominating the Khaliphs at their will. The Turks Embrace Mohammedanism.