ɪt wʌz fˈɔːɹmd ɪnðə jˈɪɹ tˈuːhˈʌndɹɪd nˈaɪnti fˈaɪv, dˈʊɹɹɪŋ ðə tˈɛtɹɑːɹki ɹᵻfˈɔːɹm ʌv ɹˈoʊmən ˈɛmpɚɹɚ dɪəklˈɛʃən, ænd ɐsˈaɪnd tə ðə sˈɪvəl dɪoʊsˈiːz ʌv pænˈoʊniə, wˌɪtʃ wʌz ɐtˈætʃt ɪnðə fˈoːɹθ sˈɛntʃɚɹi tə ðə pɹiːtˈoːɹiən pɹˈiːfɛktʃɚɹ ʌv ɪlˈɪɹɪkəm, ænd lˈeɪɾɚ tə ðə pɹiːtˈoːɹiən pɹˈiːfɛktʃɚɹ ʌv ˈɪɾəli.
It was formed in the year 295, during the Tetrarchy reform of Roman emperor Diocletian, and assigned to the civil diocese of Pannonia, which was attached in the fourth century to the Praetorian prefecture of Illyricum, and later to the Praetorian prefecture of Italy.