In 180 BC, during his early reign the Dalmatians and Daorson declared themselves independent from Gentius's rule and the city of Rhizon abandoned him prior to his defeat, receiving immunity from the Romans. He married the daughter of the Dardanian King Monunius.
In 171 BC, Gentius was allied with the Romans against the Macedonians, but in 169 BC he changed sides and allied himself with Perseus of Macedon. The southernmost city of the Ardiaean State of Gentius was Lissus, a situation established sine the First Illyrian War. He arrested two Roman legati, accusing them of not coming as emissaries but as spies. Gentius destroyed the cities of Apollonia and Dyrrhachium, which were allied with Rome. In 168 BC, he was defeated at Scodra by a Roman force under L. Anicius Gallus, in only twenty or thirty days, and in 167 brought to Rome as a captive to participate in Gallus's triumph, after which he was interned in Iguvium. The date of his death is unknown. After his defeat, the Romans split the region into three administrative divisions, called meris. The extent of the first meris is not known, while the second was Labeates, and the third was Acruvium, Rhizon, Olcinium and their environs.
The legend on the coins was in ancient Greek, and is as follows: (Greek: ΒΑΣΙ ΓΕΝ), or (Greek: ΒΑΣΙΛΕΩΣ ΓΕΝΘΙΟΥ) which came from Scodra.