[2] Although his origins are actually unknown,[3] an Athenian inscription dated to 330 BC honors Reboulas, brother of Cotys and son of king Seuthes.
[7] Cotys' precise standing at the time remains obscure, but he is tentatively identified as a brother of Hebryzelmis,[8] who was the Odrysian king in Thrace in 386/385 BC, when he was honored in an Athenian decree.
[10] With the help of Iphicrates, Cotys succeeded in establishing himself as the heir of Hebryzelmis,[11] and eliminating the opposition of his rivals, possibly including Amadocus II and Saratocus.
[12] Archaeological finds of items inscribed for Cotys to the north and west suggest expansion and contacts in that direction that have escaped the narrative sources.
[13] The name of Cotys (in one instance described as a son of the god Apollon) appears several times on objects from the Rogozen Treasure, although the precise manner in which it came to be buried in northwestern Bulgaria, presumably in the territory of the Triballi, remains unclear.
[11] In 375 BC Cotys probably supported Hales, leader of Triballi, a powerful Thracian tribe in northwestern Thrace, in their attack on the city of Abdera.
Despite an attempt for peace between Athens and Cotys, proclaiming him an ally, Charidemus is found besieging the last remaining Athenian fortresses in the southern Chersonese again in 360 BC.
By the time Cephisodotus arrived in the last week of September 360 BC, Cotys had been murdered by two of Plato’s students from Aenus, Python and Heraclides.
While Cersobleptes managed to eliminate some of these foes with the continued support of Charidemus (who captured and executed Miltokythes in 357 BC), he had to accept a partition of the kingdom with Amadocus II and Berisades.
[22] As a former ally of Athens who became a dangerous foe, Cotys I has been portrayed in a fairly negative light in our sources, depicted as irritable, intemperate, drunken, inordinately cruel, and perfidious, most notably in the polemics of Demosthenes.