Bithynia Bithynia Adrian Ole Aakre Bithynia lies in the northwestern part of Asia Minor, between the Propontis and the Bosporus and Mysia to the west, the Euxine to the north, Phrygia and Galatia to the south, and Paphlagonia to the east.
Mountains lie to the south.
In the Byzantine era the Sangarius River formed the eastern boundary. When the Younger Pliny governed this province in AD 103-5 he was actually in charge of two provinces, Bithynia and Pontus, for better administrative control. The chief cities are Chalcedon, Heraclea, Prusa, Nicaea, and the provincial capital Nicomedia. The province was prosperous because of its extensive fertile valleys, abundant game, coal at Heraclea, good harbors, and the fact that the main imperial road from Thrace to the eastern part of the empire ran though Bithynia. Despite its wealth, Bithynia's finances were always in disorganization and its people discontented.