Due to the fact that Byzantine-Persian war also started in this time, the Byzantine Empire was not able to defend Pannonia.
dˈuː tə ðə fˈækt ðæt bˈɪzɐntˌiːnpˈɜːʒən wˈɔːɹ ˈɔːlsoʊ stˈɑːɹɾᵻd ɪn ðɪs tˈaɪm, ðə bˈɪzɐntˌiːn ˈɛmpaɪɚ wʌz nˌɑːt ˈeɪbəl tə dᵻfˈɛnd pænˈoʊniə.