Complex sentence: Philip II took the most of the concept to heart but he too viewed it as a method reserved for the Greeks and it was his driving force in creating the Corinthian League an alliance to unite the Greek States for a war against the Persian Empire.
Split into simpler sentences: Philip II took much of the concept to heart, but he too viewed it as a method reserved for the Greeks. He used the concept as his driving force behind creating the Corinthian League, an alliance to unite the Greek States for a war against the Persian Empire.