Coins from Odrysian Kingdom
The Odrysian Kingdom was a state union of over 40 Thracian tribes and 22 kingdoms that existed between the 5th century BC and the 1st century AD. It consisted mainly of present-day Bulgaria, spreading to parts of Southeastern Romania (Northern Dobruja), parts of Northern Greece and parts of modern-day European Turkey.

The Odrysian kingdom had maintained continuity with its own kings, but broken up into several kingdoms (including Canite and Odrissae) by the early second century BC, until succumbing to complete Roman conquest in 146 BC. In 100 BC a Thracian kingdom was restored, possibly by a son of Beithys, one of the last kings of the Odrissae, it is not clear if it was a vassal of Rome or entirely independent. The Odrysian king was murdered by his wife and his kingdom was completely subjected to Rome in 46 AD.

Odrysian Kingdom

(1) Rhoemetalces III | Caligula 38-41 AD
AE unit Thrace
Obverse: Diademed draped bust of Rhoemetalces III left; BAΣIΛEYΣ_POIMHTAΛKAΣ
Reverse: Laureate head of Caligula left; ΓAIΩ KAIΣAP_I ΣEBAΣΤΩ
Ref: Caligula RPC 1723; BMC 2; Jurukova ...
(2) Rhoemetalces I | Augustus 11 BC - 12 AD
AE unit Thrace
Obverse: Diademed head of Rhoemetlalces I right; BAΣIΛEΩΣ__POIMHTAΛK_OY
Reverse: Bare head of Octavian Augustus right; KAIΣAPOΣ__ΣEBAΣTOY
Ref: RPC I 1718; Youroukova 194; BMC Thr...