Theoktistos continued the persecution of the Paulicians, which had been initiated by Theodora in 843. Many fled to Arab territory, where with Umar al-Aqta's aid they established a state of their own at Tephrike under their leader Karbeas. Theoktistos concluded a truce with the Abbasid Caliphate and arranged an exchange of prisoners that took place on 16 September 845. Nevertheless, in the same year, the execution of the surviving Byzantine prisoners from the Arab Sack of Amorium in 842 took place in the Abbasid capital, Samarra. After 845, the Arab raids in the east died down for a few years after a winter raid launched by Ahmad al-Bahili, the Abbasid emir of Tarsus, was defeated by the "strategos" of Cappadocia. They did not recommence until 851, when the new emir of Tarsus, Ali al-Armani, launched summer raids for three successive years, albeit with little apparent impact. The Byzantines responded with a naval expedition in 853 that sacked the port of Damietta in Egypt, while in the next year a Byzantine army invaded Arab lands in Cilicia and sacked Anazarbus. Around 20,000 prisoners were taken, some of whom were executed on Theoktistos' orders after they refused to convert to Christianity, probably as a gesture of retaliation for the Caliphate's execution of the prisoners of Amorium in 845.