Troublesome enemies as the Arab tribes had often proved to the subjects of the Roman and Persian empires, no one had ever dreamed that they could constitute a menace to either. It is true that when the Moslem inroads began, the districts first affected were in a sorry plight. The frequent wars between the Romans and Persians had sorely enfeebled both empires, and this was more particularly the case with the last great war, which had lasted from 607 to 628. Large areas of Roman territory, especially in Palestine, Syria, and Egypt, had been frightfully ravaged and occupied for years by the Persians. The valiant and wily emperor Heraclius, however, succeeded in turning the tide of fortune, and ultimately dictated terms of peace to the Persians on their own soil. After that the Persian empire had been torn asunder by quarrels over the succession. Both empires had lost the Arab outpost they once possessed. The Persians had annihilated the Roman vassal kingdom of the Ghassanids, and their own subject dynasty in Hira (which had latterly adopted the Christian faith) had been dethroned by King Chosroes II. The folly of this was soon apparent. The Bedouins of the Shaiban tribe utterly routed the royal armies of Persia at Ibu Kar on the frontiers of Babylonia, probably at the very time when the king’s forces were pursuing their victorious progress through the distant west. It was not a great battle, and probably its only direct consequence was that the unwarlike peasants of neighbouring districts were pillaged by the Bedouins; but a victory over an army composed in part of regular troops gave the Arabs confidence. This very Shaiban tribe distinguished itself in the first Moslem advance into Persian territory.