The Persian homeland was in what is now known as Iran. The Persian empire thrived after its kings such as Cyrus the great conquered the neighbouring lands.
The city of Persepolis, built by the King Darius I, was a magnificent example of the Persian tradition. Even now, through the ruins of the city, one could depict the grandeur of the palaces. But they all were destroyed during the course of the wars.
First the Persians conquered Babylon, then Egypt, then Greece, until… Alexander the great was born and who fought back and invaded the Persian empire. Alexander defeated King Darius III’s massive army at the battle of Issus. After that there was a sudden decline of the Persian empire.