Bayan nasarar yakin da aka yi da Rascia, kasar Serbia ta tsakiya, ci gaba da fadada Bulgaria zuwa yamma ya isa kan iyakokin Croatia.Sojojin Bulgaria sun mamaye Croatia kimanin a cikin 853 ko 854 a arewa maso gabashin Bosnia, inda Croatia da Bulgaria ke kan iyaka a lokacin.A cewar majiyoyin da aka samu, an gwabza kazamin fada guda daya ne kawai tsakanin sojojin Bulgaria da dakarun Croatia.Majiyoyi sun ce sojojin da suka mamaye karkashin jagorancin dan kasar Bulgariya Khan Boris na daya sun yi yaki da dakarun Duke Trpimir a yankin tsaunuka na arewa maso gabashin Bosnia da Herzegovina a yau a shekara ta 854. Ba a san takamaiman wuri da lokacin yakin ba saboda rashin samun na zamani. lissafin yakin.'Yan Bulgaria da Croatia ba su samu nasara ba.Ba da daɗewa ba bayan haka, Boris na Bulgaria da Trpimir na Croatia sun koma diflomasiyya kuma sun cimma yarjejeniyar zaman lafiya.Tattaunawar ta haifar da samar da zaman lafiya na dogon lokaci tare da iyaka tsakanin Duchy na Croatia da Bulgarian Khanate ya daidaita a kogin Drina (tsakanin Bosnia da Herzegovina na zamani da Jamhuriyar Serbia).