_Seleucus I_. (Nicator) (312-280 B.C.) was the founder of the Syrian kingdom. From Babylon he extended his dominion to the _Black Sea_, to the _Jaxartes_, and even to the _Ganges_, so far as to make the Indian prince, _Sandracottus_, acknowledge him as suzerain. From Babylon he removed his capital to _Antioch_ on the Orontes, which he founded,--a city destined to be the rival of Alexandria among the cities of the East. The effect of this removal, however, was to loosen his hold upon the Eastern provinces of his empire. _Seleucia_, on the west bank of the Tigris, he likewise founded, which became a great commercial city, but was outstripped later by the Parthian city opposite, _Ctesiphon_. The provinces beyond the Euphrates he committed to his son, _Antiochus_. With him (Antiochus I.) begins the decline of the empire through the influence of Oriental luxury and vice. Under him Syria lost the eastern part of Asia Minor through the invading Gauls, who converted northern Phrygia into _Galatia_, while north-western Lydia became the kingdom of _Pergamon_. _Antiochus II_. (261-246 B.C.) could not hold the provinces in subjection. The Parthian and Bactrian kingdoms began under his reign. _Antiochus III_. (the Great) (223-1876.0.) checked the Parthians and Bactrians, and expelled the Egyptians from Asia, but prepared for the downfall of the Syrian Empire by provoking the hostility of the Romans. BACTRIA, PARTHIA, PERGAMON, GALATIA.--_Bactria_, after it broke off from Syria, was under Greek princes until, having been weakened by the Parthians, it was conquered by the Scythians (134 B.C.). The _Parthians_ issued, as marauders, from the north border of _Iran_ (256 B.C.), under the _Arsacidae_. They gradually acquired civilization from contact with Greek culture, especially after they established the trading-city of _Ctesiphon_. About 200 B.C. the rulers of _Pontus_ made the Greek city of _Sinope_ their residence, and attained to a high degree of strength under _Mithridates VI_. (the Great). _Pergamon_ became a flourishing state under the Greek rule of _Attalus I_. (241 B.C.). It was famed for its wealth and its trade. _Eumenes II_. (197-159 B.C.) founded the library at Pergamon. For him parchment was improved, if not invented, the Egyptians having forbidden the exportation of papyrus. _Galatia_ was so named from the swarm of Gallic invaders (about 279 B.C.), who, after incursions in the East, which were continued for forty years, settled there, and by degrees yielded to the influences of Greek culture.