The Odrysian kingdom (; Ancient Greek: ) 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 amalgamation dominated by the Odrysians and the first larger political entity to develop in the eastern Balkans. Before the foundation of Seuthopolis in the late 4th century it had no fixed capital. The Odrysian kingdom was founded by king Teres I, exploiting the collapse of the Persian presence in Europe due to 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 the state showed first signs of fatigue, although the skilled Cotys I initiated a brief renaissance that lasted until his murder in 360. 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. A much smaller Odrysian state was revived in around 330 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. History Background Thrace and its early history Since the ancient Thracians lacked an indigenous writing tradition, the most important sources for the reconstruction of their history are archaeological remains, coins as well as accounts of ancient Greek historians. Said historians considered the Thracians to be a numerous people and their country, Thrace, to be of barely comprehensible size, so large that Andron of Halicarnassus (4th century BC) thought of it as a continent of its own. While the boundaries of Thrace fluctuated throughout history, Thrace can be divided in a northern and a southern half,