The struggle with the Persians was an inheritance from earlier times. [10] Under an ambitious king, Chosroes II, the Persians overran all the Asiatic provinces of the empire. A savior arose, however, in the person of the Roman emperor, Heraclius (610-641 A.D.). His brilliant campaigns against Chosroes partook of the nature of a crusade, or "holy war," for the Persians had violated the Holy Sepulcher at Jerusalem and had stolen away the True Cross, the most sacred relic of Christendom. Heraclius recovered all his provinces, but only at the cost of a bloody struggle which drained them of men and money and helped to make them fall easy victims to foes still more terrible than the Persians. These were the Arabs. ARABS Heraclius had not closed his reign before he saw all his victories undone by the advance of the Arabs. The first wave of invasion tore away Syria and Egypt from the empire, penetrated Asia Minor, and reached the shores of the Bosporus. Repulsed before the walls of Constantinople, the Arabs carried their arms to the West and seized North Africa, Spain, part of southern Italy, and the Mediterranean islands. Asia Minor and the Balkan peninsula still held out, however, and during the tenth century a line of able rulers at Constantinople succeeded in winning back some of their lost provinces. SELJUK TURKS During the eleventh century the empire had to face new enemies. These were the Seljuk Turks, [11] fierce nomads from the steppes beyond the Caspian. After their conversion to Mohammedanism, they swept with irresistible force through the East and conquered nearly all Asia Minor. The ruin of this country, in earlier ages one of the most populous and flourishing regions of the world, dates from its occupation by the Seljuks. To resist their further advance the Roman emperor sought in 1095 A.D. the help of the Christians of Europe. His appeals for aid resulted in the First Crusade, with which a new chapter of medieval history began. (See Chapter XX.) WORK OF THE EMPIRE IN ASIA Thus, for more than five centuries after Justinian, the Roman Empire in the East was engaged in a long struggle with the foes--Persians, Arabs, and Seljuk Turks--which successively attacked its dominions. By its stubborn resistance of the advance of the invaders the old empire protected the young states of Europe from attack, until they grew strong enough to meet and repulse the hordes of Asia. This service to civilization was not less important than that which had been performed by Greece and Rome in their contests with the Persians and the Carthaginians. 117. THE EMPIRE AND ITS FOES IN EUROPE SLAVS