Persia, Ancient, ancient high plateau of Iran, home of several great civilizations. In 2nd millennium B.C. the literate civilization of Elam developed in the southwest of the plateau, with its capital at Susa. It was ended in 639 B.C. by the invasion of Ashurbanipal of Assyria. Assyrian downfall followed in 612 after the sacking of Nineveh by the Babylonians and the Medes. The area of Parsumash to the south of the Medes was ruled by the Achaemenians. Cyrus the Great expanded the Achaemenid empire, and at his death (529) he controlled the Middle East from the Mediterranean to the Indus River. Under Darius I (522–486) a road system linked the great empire and a canal linked the Nile and Red Sea. Flourishing trade, commerce, and public works continued under Xerxes I (586–465). Xerxes' murder by his son was followed by intrigues and rebellions that weakened the Achaemenians. In 330 the empire was conquered by the Parthians. The empire of Parthia (3rd century B.C. to 3rd century A.D.) halted the nomads in the northeast and the Romans in the west, defeating Crassus in 53 B.C. and later Mark Antony. In c.A.D. 224, a successful revolt by Ardashir, ruler of the Fars (the southern Persian homeland), established the vigorous Sassanian empire. Arts, architecture, and religion (Zoroastrianism) revived, the wars with Rome continued, and in 260, Shapur, the son of Ardashir, captured the Emperor Valerian. After constant struggles with the Byzantines, the Sassanian empire was overwhelmed by the Arabs and converted to Islam in 651.