The Persians could not conquer the Greek mainland in 479 B.C.E. After that, the Persian Empire and its Achaemenid leaders began to lose power. The kings after Xerxes were weak.
At the same time, the Greek city-states grew stronger. Philip of Macedonia united them into the Hellenic League. He named himself and his heirs leaders of the league. Philip was murdered in 336 B.C.E. In 334, his son, Alexander, decided to invade Persia. Philip’s son was later known as Alexander the Great.
