The reason is simple.

Persia is not a sea power and is land locked in Asia Minor and on the East Mediterranean coast with a formidable array of soldiers from many nations.

The Phoenicians, on the other hand, have the fleets, the navigators, the seamen and the "know-how". Guided by the stars they sail at night over dark, dangerous, uncharted waters, guided only by the stars. An arrangement is therefore reached with the kings of the Phoenician cities to furnish a fleet to the Persians provided they are not bothered by them at home.

Soon after Greece is invaded by Xerxes, the Persian "King of Kings". Bloody battles on land and sea follow. Sporadic fighting spreads to the Greek islands and Cyprus.

Then in 333 B.C. Alexander the Great at the head of his Macedonian phalanxes crosses the Hellespont in pursuit of Darius Codamannus, the Persian king, thus bringing the war into Asia. City after city go over to him.

Alexander's conquest of the East ushurs in the Hellenistic Age. With the spread of Greek culture and ideas, a new political and social order arises and travels to the farther reaches of his empire contributing to fashion the course of the modern world in which we live.