Achaemenids ruled the Persian Empire from about 550 BC to 330 BC. It was named for Achaemenes, a minor ruler of south-western Iran, but the real founder of the dynasty was his great- great-grandson, Cyrus the Great, creator of the Persian Empire. At the peak 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 Syr Darya River in the north. They provided Persia with great administration, a complete code of laws, reliable currency, and efficient postal service. Although their religious was Zoroastrians, they were tolerant of other religions, and under their rule art and architecture grow in the region. The dynasty ended with the death of Darius III.