The next phase of Balkan history was under the Roman Power. When the Roman strength had reached its zenith and entered upon the curve of decay, it was on the Balkan boundaries of the Empire that the main attack came. Finally, the rulers of the Roman Empire found it necessary to concentrate their strength close to the point of attack, and the capital was moved from Rome to Constantinople: the Roman Empire became the Greek Empire. Thus, as we have seen in the previous chapter, the Balkan Peninsula was chosen as the arena in which an Empire founded in the Italian Peninsula was to die its long, uneasy death. The fate of this Greek Empire had been hardly decided when a new racial element came on the scene, and over the tottering Empire, already fighting fiercely with Bulgar and Serb for its small surviving patch of territory, strode the Turk in the full flush of his youthful strength, giving the last blow to the rule of the Caesars, and threatening all Christian Europe with conquest. Made thus by the Fates the cockpit of the great struggles for World-Empire, the Balkan Peninsula was doomed to a bloody history: and the doom has not yet passed away. Perhaps it is some unconscious effect on the mind of the pity of this that makes the traveller to the Balkans feel so often a sympathy, almost unreasonable in intensity, for the Balkan peoples. The Balkan acres which they till are home to them. To civilisation those acres are the tournament field for the battles of races and nations. What is now Bulgaria was in the days of Herodotus inhabited by Thracian and Illyrian tribes. They were united under the strong hand of Philip of Macedonia, and Bulgaria counts him the first great figure in her confused national history, and makes a claim to be the heir of his Macedonian Empire. The Romans appeared in Bulgaria during the period of the second war against Carthage. The Roman conquest of the Balkan country was slow, but shortly before the Christian era the Roman provinces of Moesia and Thracia comprised most of what is now Bulgaria.