 In 930 , Melias 's attack on Samosata was heavily defeated ; among other prominent officers , one of his sons was captured and sent to Baghdad . Later in the same year , John and his brother Theophilos besieged Theodosiopolis ( modern Erzurum ) , the capital of the emirate of Qaliqala . The campaign was complicated by the machinations of their ostensible allies , the Iberian rulers of Tao @-@ Klarjeti . Resenting the extension of direct Byzantine control adjacent to their own borders , the Iberians had already provided supplies to the besieged city . Once the city was invested , they vociferously demanded that the Byzantines hand over several captured towns , but when one of them , the fort of Mastaton , was surrendered , the Iberians promptly returned it to the Arabs . As Kourkouas needed to keep the Iberians placated and was aware that his conduct was being carefully observed by the Armenian princes , he did not react to this affront . After seven months of siege , Theodosiopolis fell in spring 931 and was transformed into a tributary vassal , while , according to Constantine VII 's De Administrando Imperio , all territory north of the river Araxes was given to the Iberian king David II . As in Melitene , the maintenance of Byzantine control over Theodosiopolis proved difficult and the population remained restive . In 939 , it revolted and drove out the Byzantines , and Theophilos Kourkouas could not finally subdue the city until 949 . It was then fully incorporated into the Empire and its Muslim population was expelled and replaced by Greek and Armenian settlers . 
