The Bithynians were a Thracian people occupying the NW corner of Asia Minor on the Asian side of the Bosphorus. This list runs from their independence from Persia. In 297 BC a local dynast, Ziboetes, declared himself king and successive kings increasingly Hellenised the country. They maintained their independence against a succession of powerful and often aggressive neighbours until Nikomedes III was unable to resist Mithridates of Pontus, was rescued by a Roman army and later bequeathed the kingdom to Rome. On his death it became part of the new Roman province of Bithynia et Pontus. The terrain consisted of very fertile valleys separated by forested mountains, the peaks of which were snow capped well into summer. Early foot fought with javelins and there is no evidence for long spears or rhomphaia. Stelae of the second century BC show thureophoroi and armoured cavalry and one mentions infantry operating with advance cavalry. Persian cavalry helped against the mercenary Ten Thousand commanded by Xenophon fighting to get back home in 400 BC after being on the losing side in a Persian civil war. The Galatians that had rampaged through Greece were first invited into Asia by Nikomedes I of Bythinia in 278 BC to help him in a civil war, later establishing a neighbouring kingdom of their own in the interior. Reference: Armies of the Macedonian and Punic Wars D. Head, The Anabasis Xenophon.
— Bithynian Army 435 BC - 74 BC
I/60 — EARLY ACHAEMENID PERSIAN 550 BC - 420 BC
II/12 — ALEXANDRIAN MACEDONIAN 359 BC - 319 BC
II/14 — ARIARATHID KAPPADOKIAN 330 BC - 322 BC & 300 BC - 17 AD
II/15 — ALEXANDRIAN IMPERIAL 328 BC - 321 BC
II/16 — ASIATIC EARLY SUCCESSOR 320 BC - 285 BC
II/17 — LYSIMACHID 320 BC - 281 BC
II/30 — GALATIAN 280 BC - 25 BC
II/34 — ATTALID PERGAMENE 263 BC - 129 BC
II/48 — MITHRIDATIC 110 BC - 47 BC
II/5 — LATER HOPLITE GREEK 448 BC - 225 BC
II/6 — BITHYNIAN 435 BC - 74 BC
II/7 — LATER ACHAEMENID PERSIAN 420 BC - 329 BC
II/30 — GALATIAN 280 BC - 25 BC