A barrier grew between the Near East and Greece, as a result of the Persian Wars. It took until the middle of the following century to break the barrier.
The first Persian War was in 490 B.C. and the purpose was to get back at Athens for raiding Asia Minor. The second Persian War was in 481 B.C. and the purpose was to conquer all Greek states. The third Persian War, led by Xerxes, in 480 B.C. was a second attempt to overtake the Greek states, but it was a failure. After this final attempt, Persian expansionism stopped threatening Greece.