280. Seleucus, the last of Alexander's captains, is assassinated. Of all Alexander's successors, Seleucus had formed the most powerful empire. He had acquired all the provinces between Phrygia and the Indus. He extended his dominion in India beyond the limits reached by Alexander. Seleucus had some sparks of his great master's genius in promoting civilization and commerce, as well as in gaining victories. Under his successors, the Seleucidae, this vast empire rapidly diminished; Bactria became independent, and a separate dynasty of Greek kings ruled there in the year 125, when it was overthrown by the Scythian tribes. Parthia threw off its allegiance to the Seleucidae in 250 B.C., and the powerful Parthian kingdom, which afterwards proved so formidable a foe to Rome, absorbed nearly all the provinces west of the Euphrates, that had obeyed the first Seleucus. Before the battle of Ipsus, Mithridates, a Persian prince of the blood-royal of the Achaemenidae, had escaped to Pontus, and founded there the kingdom of that name. Besides the kingdom of Seleucus, which, when limited to Syria, Palestine, and parts of Asia Minor, long survived; the most important kingdom formed by a general of Alexander was that of the Ptolemies in Egypt. The throne of Macedonia was long and obstinately contended for by Cassander, Polysperchon, Lysimachus, Pyrrhus, Antigonus, and others; but at last was secured by the dynasty of Antigonus Gonatas. The old republics of southern Greece suffered severely during these tumults, and the only Greek states that showed any strength and spirit were the cities of the Achaean league, the AEtolians, and the islanders of Rhodes. 290. Rome had now thoroughly subdued the Samnites and the Etruscans, and had gained numerous victories over the Cisalpine Gauls. Wishing to confirm her dominion in Lower Italy, she became entangled in a war with Pyrrhus, fourth king of Epirus, who was called over by the Tarentines to aid them. Pyrrhus was at first victorious, but in the year 275 was defeated by the Roman legions in a pitched battle. He returned to Greece, remarking, "Rome becomes mistress of all Italy from the Rubicon to the Straits of Messina."