In the contests which the successors of Alexander carried on for the supremacy after his death, the valley of the Euphrates and Tigris, and the table-land of Iran, finally fell to the lot of Seleucus. But in the middle of the third century (256 B.C.), Arsaces in Parthia and the satrap Diodotus in Bactria rebelled against the second successor, Antiochus Theos. The descendants of Arsaces not only succeeded in maintaining their independence against the Seleucids, in spite of severe reverses, but Mithridates I., the sixth Arsacid (174-136 B.C.), united all Iran under his dominion. The Greeks lost their supremacy, and Iran again became subject to native princes. Meanwhile Diodotus had founded an independent supremacy in Bactria. His son, of the same name, was succeeded by Euthydemus, against whom, towards the year 200 B.C., Antiochus III. marched, in order to force Bactria to submission. Euthydemus was defeated at the river Areios (p. 10), and fled to Zariaspa. By the surrender of his elephants he obtained an established recognition from Antiochus. Demetrius and Eucratides, the successors of Euthydemus (after 180 B.C.), extended the sphere of their dominion to the east over the land on the Cabul to the Indus. The kingdom of Chandragupta, Vindusara, and Açoka, which, as we know, included the east of Iran, and has left us inscriptions at Peshawur (IV. 525), fell to pieces under Açoka's grandsons. Apollodorus of Artemita told us above that the fertility of the Bactrian soil enabled the Greek rulers to make important conquests (p. 12); he informs us that Eucratides founded the city of Eucratideia in Bactria, and subjugated a thousand cities in India. We may assume that Bactria under these princes was not merely powerful, but prosperous. According to the statement of Justin, a thousand cities were at that time enumerated in Bactria,[41] and we possess satisfactory evidence that these rulers and their courts, and the Greek settlements which Alexander founded in the distant East, were able permanently to establish the style and art of Hellas. The coins of these princes, who are designated in Greek as "kings," "great," "invincible," rival the best work which proceeded from Greek mints. The faces present the heads of the princes, in characteristic and individual portraits; the reverses exhibit Heracles, Athena, Apollo with a crown of rays, the Dioscuri on horseback, lance in hand. But by degrees the national types of the East are again employed on these coins. The reverse presents the galloping horse, the animal of Bactria, the elephant, and the humped ox.[42] The head of Demetrius, who first conquered territory in India, and that of some of his descendants, is covered by a helmet adorned with the tusks and trunk of an elephant. Besides the round, numbers of rectangular coins have also been found, from which we can discover the native traditional form of the Bactrian coinage. After the reign of Eucratides these rectangular coins present