=98.= Bactria was a part of the Syrian empire from 305 to 255 B. C. Diodotus, the satrap, then made himself independent, and established a new Greek kingdom, the most easterly of all the scattered fragments of Alexander’s conquests. Euthydemus, the third king, was a native of Magnesia, and a usurper (B. C. 222-200). His son Demetrius made many victorious campaigns, extending over Afghanistan and into India (B. C. 200-180). He lost a part of his native dominions to a rebel, Eucrat´ides, who reigned north of the Pa´ropam´isus range during the life of Demetrius, and after his death, over the whole country. He, too, carried on Indian wars with great energy and success. Under his son, Heli´ocles (B. C. 160-150), the Bactrian kingdom rapidly declined, being invaded by the Parthian kings on the west, and the Tartar tribes from the north. XI. PARTHIAN EMPIRE OF THE ARSACIDÆ. =99.= The Parthians established their independence about B. C. 250, under the lead of the Scythian Arsaces. The people were of the same race with the modern Turks—treacherous in war, indolent and unaspiring in peace, rude in arts and barbarous in manners. Their warlike hardihood, however, gave the Romans a more troublesome resistance than they encountered in any other portion of Alexander’s former empire; and the dominion of the Arsacidæ lasted nearly 500 years, until it was overthrown by the new Persian kingdom, A. D. 226. The greatness of the Parthian empire dates from Mithridates, who is also called Arsaces VI., B. C. 174-136. The neighboring kingdom of Bactria, with its Greek monarchs and its higher civilization, had hitherto maintained the ascendency; but while these kings were absorbed in their Indian conquests, Mithridates seized upon several of their provinces, and eventually absorbed their whole dominion. [Illustration: Coin of Arsaces III., twice the size of original.] The Parthian empire, at its greatest extent, comprised all the countries between the Euphrates and the Indus; from the Araxes and the Caspian on the north, to the Persian Gulf and Indian Ocean on the south. Its numerous parts were not consolidated into one government, as were the satrapies of Persia or the provinces of Rome; but each nation, with its own laws and usages, retained its native king, who was tributary to the lord-paramount in the Arsacid family. Hence the Parthian coins, like the Assyrian monuments, commonly bear the title “King of Kings.” The wars of Mithridates made the Euphrates the boundary-line between the Parthian and Roman empires. The wealth and power of the Oriental monarchy provoked at once the avarice and the jealousy of the western Republic, and a collision could not long be delayed. The details of the Parthian wars of Rome will be found in Book V. RECAPITULATION.