What is the Persian War

The Persian Empire took control of Asia Minor in the 6th Century BCE. Included in this were the Greek cities which dotted the Mediterranean and Black Sea coast. Mainland Greek cities supported revolutions of those ‘daughter’ colonies in Asia, and the Persians looked to punishing this interference, and to establish a longer term ethnic frontier by incorporating mainland Greece within the Empire.
King Darius planned this, and to punish the Athenian and Euboean assistance to Miletus which resulted in burning of Sardis, the Asia Minor province of the Empire, an amphibious expedition was sent in 490 BCE which reduced Euboea but failed in defeat at Marathon and before the walls of Athens. A second major expedition was planned but was delayed by the death of Darius and prior commitment to capture of Egypt.
However by 480 BCE the new emperor King Xerxes had assembled a new and larger naval and land expeditionary force, subverted most of the northerly Greek city states, and captured Athens after defeating an abortive attempt to destroy his fleet off the pass at Thermpopylae. His force was defeated by a sea battle – Salamis 480, the land battle at Plataia 479 and the sea-land battle at Mykale 479.
For further detail see WikiAnswers question:
http://wiki.answers.com/Q/Who_won_the_battle_with_the_300

The Athenians then established an anti-Persian alliance of the mainland and Asian greek states, which it progressively converted to an empire of its own, the proceeds from which ended up financing the great buildings of the city, and also stimulated the 27-year war between Athens and its empire and Sparta and its allies. Athens lost after the intervention of Persian money allowed Sparta to build up a navy to rival Athens’. The Persians continued to sit on the sidelines through the 5th and 4th Centuries BCE, preferring to exercise control through financial influence rather than fighting as the Greek cities weakened themselves fighting each other. This was reversed only after Philip of Macedonia and then his son Alexander gained control of mainland Greece in the second half of the 4th Century BCE, and the latter then invaded and defeated the Persian Empire. The empire was split up between Alexander’s successors after his death.
For further detail see WikiAnswers question:
http://wiki.answers.com/Q/What_happened_to_Alexander_The_Great’s_empire_after_his_death
In the Eastern Mediterranean 499-449 BCE.