Ci gaba da nasarar da Ivaylo ya samu a kan ƙarfafawar Rumawa ya sa Ivan Asen III ya gudu daga babban birnin kasar ya tsere zuwa Daular Rumawa, yayin da George Terter I ya kama mulki a matsayin sarki a shekara ta 1280. Tare da barazanar Ivaylo da Ivan Asen na III, George Terter I ya yi nasara. kawance da Sarki Charles I na Sicily, da Stefan Dragutin na Serbia, da kuma Thessaly a kan Michael VIII Palaeologus na Daular Byzantine a 1281. Ƙungiyar ta gaza yayin da Charles ya shagala da Sicilian Vespers da ballewar Sicily a 1282, yayin da Bulgaria ta kasance. Mongols na Golden Horde ya lalata su a karkashin Nogai Khan.Neman goyon bayan Serbia, George Terter I ya haɗa 'yarsa Anna zuwa ga Sarkin Serbia Stefan Uroš II Milutin a 1284.Tun bayan mutuwar Sarkin Rumawa Michael na VIII Palaiologos a shekara ta 1282, George Terter I ya sake bude tattaunawa da Daular Rumawa kuma ya nemi ya dawo da matarsa ​​ta farko.An cimma wannan ta hanyar yarjejeniya, kuma Marias biyu sun yi musayar wurare a matsayin sarki da garkuwa.Shi ma Theodore Svetoslav ya koma Bulgaria bayan nasarar da sarki Joachim III ya yi masa, kuma mahaifinsa ya nada shi tare da zama sarki, amma bayan wani mamayar Mongol a 1285, an kore shi a matsayin garkuwa ga Nogai Khan.Ita ma sauran 'yar'uwar Theodore Svetoslav, Helena, an aika zuwa Horde, inda ta auri ɗan Nogai Chaka.Dalilan gudun hijira ba su fito fili ba.A cewar George Pachymeres, bayan harin da Nogai Khan ya kai Bulgaria, an cire George Terter daga karagar mulki sannan ya tafi Adrianople.Sarkin Byzantine Andronikos II Palaiologos da farko ya ƙi karbarsa, watakila yana jin tsoron rikici da Mongols, kuma George Terter yana jira a cikin mummunan yanayi a kusa da Adrianople.Daga karshe aka tura tsohon sarkin Bulgaria ya zauna a yankin Anatoliya.George Terter I ya wuce shekaru goma masu zuwa na rayuwarsa a cikin duhu.