|Ancient Region of Anatolia|
|State existed:||297-74 BC|
|Historical capitals||Nicomedia, Nicaea|
According to Strabo Bithynia was bounded on the east by the river Sangarius (modern Sakarya river), but the more commonly received division extended it to the Parthenius, which separated it from Paphlagonia, thus comprising the district inhabited by the Mariandyni. On the west and southwest it was separated from Mysia by the river Rhyndacus; and on the south it adjoined Phrygia, Epictetus and Galatia.
It is occupied by mountains and forests, but has valleys and coastal districts of great fertility. The most important mountain range is the (so-called) "Mysian" Olympus (7600 ft., 2300 m), which towers above Bursa and is clearly visible as far away as Istanbul (70 miles, 113 km). Its summits are covered with snow for a great part of the year.
East of this the range extends for more than 100 miles (160 km), from the Sakarya to Paphlagonia. Both of these ranges are part of the border of mountains which bounds the great tableland of Anatolia,Turkey. The broad tract which projects towards the west as far as the shores of the Bosporus, though hilly and covered with forests - the Turkish Ağaç Denizi, or "The Ocean of Trees" - is not traversed by any mountain chain. The west coast is indented by two deep inlets, the northernmost, the Gulf of İzmit (ancient Gulf of Astacus), penetrating between 40 and 50 miles (65-80 km) into the interior as far as İzmit (ancient Nicomedia), separated by an isthmus of only about 25 miles (40 km) from the Black Sea; and the Gulf of Mudanya or Gemlik (Gulf of Cius), about 25 miles (40 km) long. At its extremity is situated the small town of Gemlik (ancient Cius) at the mouth of a valley, communicating with the lake of Iznik, on which was situated Nicaea.
The principal rivers are the Sakarya which traverses the province from south to north; the Rhyndacus, which separated it from Mysia; and the Billaeus (Filiyas), which rises in the Aladağ, about 50 miles (80 km) from the sea, and after flowing by modern Bolu (ancient Bithynion-Claudiopolis) falls into the Euxine, close to the ruins of the ancient Tium, about 40 miles (64 km) northeast of Heraclea Pontica (the modern Karadeniz Ereğli), having a course of more than 100 miles (160 km). The Parthenius (modern Bartın), the eastern boundary of the province, is a much less considerable stream.
The valleys towards the Black Sea abound in fruit trees of all kinds, such as oranges, while the valley of the Sangarius and the plains near Bursa and Iznik (Nicaea) are fertile and well cultivated. Extensive plantations of mulberry trees supply the silk for which Bursa has long been celebrated, and which is manufactured there on a large scale.
According to ancient authors (Herodotus, Xenophon, Strabo, etc.), the Bithynians were an immigrant Thracian tribe. The existence of a tribe called Thyni in Thrace is well attested, and the two cognate tribes of the Thyni and Bithyni appear to have settled simultaneously in the adjoining parts of Asia, where they expelled or subdued the Mysians, Caucones and other minor tribes, the Mariandyni maintaining themselves in the northeast. Herodotus mentions that the tribe Thyni and Bithyni as existing side by side; but ultimately the latter must have become the more important, as they gave their name to the country. They were incorporated by king Croesus within the Lydian monarchy, with which they fell under the dominion of Persia (546 BC), and were included in the satrapy of Phrygia, which comprised all the countries up to the Hellespont and Bosporus.
Bithynia appears to have attracted so much attention because of its roads and its strategic position between the frontiers of the Danube in the north and the Euphrates in the southeast. Troops frequently wintered at Nicomedia.
The most important cities were Nicomedia and Nicaea. The two had a long rivalry with one another over which city held the rank of capital. Both of these were founded after Alexander the Great; but at a much earlier period the Greeks had established on the coast the colonies of Cius (modern Gemlik); Chalcedon (modern Kadıköy), at the entrance of the Bosporus, nearly opposite Byzantium (modern Istanbul; and Heraclea Pontica (modern Karadeniz Ereğli), on the Euxine, about 120 miles (190 km) east of the Bosporus. All these rose to be flourishing places of trade, as did Prusa. Other places of importance at the present day are İzmit and Scutari (modern Üsküdar).