The Achaemenid Dynasty ruled Persia from about 550BC to 330BC. It was named for Achaemenes, a minor ruler of the Anshan province, but the real founder of the dynasty was his great-great-grandson, Cyrus the Great, creator of the Persian Empire. At the zenith of their power, under Darius the Great, the Achaemenids ruled an empire extending from the Indus River in the east to Libya and Thrace in the west and from the Persian Gulf in the south to the Caucasus and the Jaxartes River in the north. They provided Persia with superb administration, a comprehensive code of laws, reliable currency, and efficient postal service. Although Zoroastrians themselves, they were tolerant of other religions, and under their rule art and architecture flourished. The dynasty ended with the death of Darius III.
This coin is from the last century of the Achaemenid Period, between Artaxerxes I and Darius III. The Siglos denomination traditionally had the image of Darius the Great upon it.