ðɪ ɛɡzˈækt bˈoːɹdɚz ʌvðə θˈiːm ʌv sˈɜːmiəm ɑːɹ ʌŋklˈɪɹ: ɐkˈoːɹdɪŋ tə sˌʌm sˈoːɹsᵻz, θˈiːm ɪŋklˈuːdᵻd ɹˈiːdʒən ʌv sˈɪəmˌiə ɔnðə nˈɔːɹðɚn bˈæŋk ʌvðə sˈɑːvɚ ɹˈɪvɚ æz wˈɛl æz pˈɑːɹts ʌv mˈɑːdɚn sˈɜːbiə ænd bˈɑːsniə ænd hˈɜːzɪɡˌɑːvɪnə ɔnðə sˈʌðɚn bˈæŋk ʌvðə sˈɑːvɚ ɹˈɪvɚ, wˈaɪl, ɐkˈoːɹdɪŋ tʊ ˈʌðɚ sˈoːɹsᵻz, ɪɾ ɛkstˈɛndᵻd ɐlˈɔŋ ðə sˈʌðɚn bˈæŋk ʌvðə dˈænuːb ænd ɐlˈɔŋ ðə ɹˈɪvɚ sˈɑːvə.
The exact borders of the Theme of Sirmium are unclear: according to some sources, theme included region of Syrmia (on the northern bank of the Sava river) as well as parts of modern Serbia and Bosnia and Herzegovina on the southern bank of the Sava river, while, according to other sources, it extended along the southern bank of the Danube and along the river Sava.