Pannonia was an ancient province of the Roman Empire bounded north and east by the Danube, coterminous westward with Noricum and upper Italy, and southward with Dalmatia and upper Moesia. Pannonia was located over the territory of the present-day western Hungary, eastern Austria, northern Croatia, north-western Serbia, Slovenia, western Slovakia and northern Bosnia and Herzegovina.
The gradual Celticization of all of Pannonia took place in the 3rd century BC. Names became Celtic, as seen in Roman times, and Celts had established control north of the Save and south and west of the Danube. In the western half and west of Pannonia the Pre-Celtic language disappeared. By the first half of the 1st century BC the language of the Illyrians in Northern Dalmatia was completely Celticized. There is an abundance of Celtic names in Illyria sometimes making the Illyrian ones seem few. Those parts of Pannonia that had not been conquered by the first Celtic invasion were already Celticized by the beginning of the 3rd century BC. The Dalmatae had been Celticized by the 3rd century BC. In the region of Pannonia as a Roman province Celticization had almost completely eradicated Illyrian culture.
Celts - Middle Danube Area. Imitation of Audoleon. Pannonia (Burgenland). Ca. 2nd CENTURY BC. AR Tetradrachm. 23mm, 12.50gr. Kroisbach mit Reiterstumpf type. Obv: Diademed head right of male with heavy brows and prominent protrusion on bridge of nose. Rev : Diademed head and torso left of rider on prancing horse; above right, eye-shaped device; twisted exergual line terminating in torques. Lanz 743–5; OTA 469; CCCBM I 152-4; KMW 1391. NGC Ch AU★ 5/5, 5/5, Fine Style.