quality:corruption, structural:expansion, information:extraction, stylistic:style_transfer
The Odrysian kingdom (/ oʊ ˈ d r ɪ ʒ ə n /; Ancient Greek: Βασίλειον Ὀδρυσῶν) was an ancient Thracian state that thrived between the early 5th century BC and the early 3rd / late 1st century BC. Located in present-day Bulgaria, southeastern Romania (Northern Dobruja), northern Greece and European Turkey, it was a tribal amalgam dominated by the Odrysians that was the first large political entity to develop in the eastern Balkans.

The Odrysian kingdom was founded by king Teres I, exploiting the collapse of the Persian presence in Europe due to the failed invasion of Greece in 480–79. Teres and his son Sitalces pursued a policy of expansion, making the kingdom one of the most powerful of its time. Throughout much of its early history it remained an ally of Athens and even joined the Peloponnesian War on its side. By 400 BC the state showed first signs of fatigue, although the skilled Cotys I initiated a brief renaissance that lasted until his murder in 360 BC.

Afterwards the kingdom disintegrated: southern and central Thrace were divided among three Odrysian kings, while the northeast came under the dominion of the kingdom of the Getae. The three Odrysian kingdoms were eventually conquered by the rising kingdom of Macedon under Philip II in 340 BC. A much smaller Odrysian state was revived in around 330 BC by Seuthes III, who founded a new capital named Seuthopolis that functioned until the second quarter of the 3rd century BC. After that there is little conclusive evidence for the persistence of an Odrysian state, with the exception of a dubious Odrysian king fighting in the Third Macedonian War named Cotys. The Odrysian heartland was eventually annexed by the Sapaean kingdom in the late 1st century BC, which was converted into a Roman province of Thracia in 45-46 AD.