BITHYNIA, a district In the north-west of Asia Minor (Gr. BtOvvia), adjoining the Propontis, the Thracian Bosporus and the Euxine (q.v.). On the east it adjoined Paphlagonia, on the west and south-west Mysia, and on the south Phrygia and Galatia. It is in great part occupied by mountains and forests, but has valleys and districts of great fertility near the sea-coast. The most important mountain range is the "Mysian" Olympus (7,60of t. ), whose summits are covered with snow for a great part of the year. The country between the mountains and the coast, covered with forests and traversed by few lines of route, is imperfectly known. The west coast is indented by two deep inlets, the Gulf of Ismid (anc. Gulf of Astacus), and the Gulf of Mu dania or Gemlik (Gulf of Cius).
The principal rivers are the Sangarius (mod. Sakaria), which traverses the province from south to north, and the Billaeus (Filiyas), which rises in the Ala-Dagh, about 50m. from the sea, and after flowing by Boli (anc. Claudiopolis) falls into the Euxine, about 4om. N.E. of Heraclea, having a course of more than loom.
The natural resources of Bithynia are imperfectly developed. Its forests would furnish vast supplies of timber if rendered accessible. Coal is known to exist near Eregli (Heraclea). The valleys towards the Black Sea abound in fruit trees of all kinds, while the valley of the Sangarius and the plains near Brusa and Isnik (Nicaea) are fertile and well cultivated. Extensive planta tions of mulberry trees supply the silk for which Brusa has long been celebrated.
The ancient Bithynians were an immigrant Thracian tribe.
Herodotus (i. 28) mentions the Thyni and Bithyni as existing side by side but ultimately the latter became the more important, and gave their name to the country. They were incorporated by Croesus (q.v.) with the Lydian monarchy, with which they fell under the dominion of Persia (S46 B.c.) . Before the conquest by Alexander the Bithynians asserted their independence, under Bas and Zipoetes, the last of whom transmitted his power to his son Nicomedes I., the first to assume the title of king. This monarch founded Nicomedia, which soon rose to great prosperity, and during his long reign (278-250 B.c.) , as well as those of his successors, Prusias I., Prusias II., and Nicomedes II. (149-91 B.c.), the kingdom of Bithynia held a considerable place among the minor monarchies of Asia. The last king, Nicomedes III., was unable to maintain himself against Mithridates of Pontus, and, after being restored to his throne by the Roman senate, he bequeathed his kingdom by will to the Romans (74 B.c.) . Bithynia now became a Roman province. Its limits were frequently varied, and it was often united for administrative purposes with the province of Pontus. This was the state of things in the time of Trajan, when the younger Pliny was appointed governor of the combined provinces, (A.D. 103-105). Under the Byzantine empire Bithynia was again divided into two provinces, separated by the Sangarius, to the west of which the name of Bithynia was restricted.
The most important cities were Nicomedia and Nicaea; both of these were founded of ter Alexander the Great ; but at a much earlier period the Greeks had established on the coast the colonies of Cius, Chalcedon, and Heraclea Pontica. All these rose to be flourishing places of trade, as also Prusa at the foot of Mt. Olympus (see BxvsA) . The only other places of importance at the present day are Kocaeli (Nicomedia) and Uskudar.
See G. Perrot, Galatie et Bithynie (1862) ; for an interesting account of Roman relations with the Christians in Bithynia see Pliny, Cor respondence with Trajan (ed. E. G. Hardy, 1889), introduction pp. 5i-65; Epp. xcvi. (xcvii.) and xcvii. (xcviii.) and appendix, pp.