The ancient province of Bithynia, corresponding roughly to central-northern Turkey, was situated on a fertile plain between Asia Minor in the west, the mountains of Galatia in the South, Pontus to the East and the Black Sea to the North. Nestled in a crossroads of trade, Bithynia flourished for centuries and was highly prized. Its valleys offered abundant grain and game; foothills provided coal, and excellent port provided a constant flow of trade goods.
Among the earliest settlers of Bithynia were migrating Thracians (c. 550 BC) who crossed the Bosporus in search of fertile land.
The Thracian people of Bithynia, originally the northern portion of Hellespontine Phrygia, broke free from Persian hegemony in the 430's, and emerged as the Kingdom of Bithynia after the demise of Alexander, quickly absorbing the southern districts. Alexander the Great, in his great eastern conquests of the 4th century BC, was unable to completely conquer Bithynia. The native peoples, resourcefully using forested, mountainous regions to their advantage were able to maintain their independence, and were among the very few who could boast of resisting Alexander. Though the Seleucids, the Macedonian dynasty that ruled large parts of modern Turkey and Syria after Alexander, controlled much surrounding territory, Bithynia remained virtually independent until the coming of Rome.
By the first century BC, internal power struggles and danger from Mithridates VI of Pontus brought Bithynia politically closer to Rome. Wars with Mithridates, and subsequent Roman intervention, secured an ousted Nicomedes III on his own throne on more than one occasion, and he had little choice in his allegiance. In fact relations between one young Roman ambassador (c. 80 BC) and the Bithynian King were so great that it would later fuel wild speculation and political fodder. Julius Caesar would later be regularly accused of homosexual relations with the King, much to the delight of his enemies. Caesar, certainly as a counter to such allegations developed a calculated strategy of building ‘relationships’ with as many Roman women as he could, including the wives of both friend and foe.
Nicomedes III, nearing the end of his life in 74 BC, and despite his good relations with Rome, still faced considerable threat from Mithridates. The internal conflicts between Marius, Sulla, Cinna, etc. never allowed Rome to completely deal with the situation in Pontus. In order to achieve stability and unlimited protection for his people directly from Rome, Nicomedes bequeathed his kingdom to Rome on his deathbed in 74 BC. The Senate immediately declared the kingdom a province, an action that would partially lead to the Third Mithiridatic War. Several years of campaigning eventually brought Pompey the Great to the east. By 65 BC, Pompey eliminated Cilician pirates, and continued the work of previous commands in removing Mithridates from power. By 62 BC, Mithridates was dead and Roman hegemony spread through the entire east, from modern Turkey to Egypt. In his settlements, Bithynia was organized as a joint province with Pontus, a political arrangement that would last until the provincial reforms of Diocletion (c. AD 270’s).
Pliny the Younger, nephew of the great author Pliny the Elder, served as Governor between AD 103 and 105. A letter writer and incidental historian in his own write, Pliny’s letters to Trajan gives us some of the best first hand source material recorded on treatment of the early Christians. Though the east faced some pressures from migratory tribes, it was far more protected than western provinces. Bithynia not only flourished as a part of the Roman Empire, when Constantine moved the capital to nearby Byzantium, it essentially formed the center of the Eastern Empire. It would remain a province of the ‘Byzantine’ Empire, at least in part, until its ultimate collapse in the 15th century. (from UNRV History)