In spring 1259, the Armenian Prince Prosh Khaghbakian, together with his Armenian Zakarid suzerain Shahnshah, led a large force of Georgians and Armenians to support a much smaller force of Mongol troops of Hulegu headed by his son Yoshmut in the siege of Mayyāfāriqīn (Diyarbakır), which was defended by its last Ayyubid ruler Al-Kamil Muhammad. Military units of Cilician Armenia also participated, and would soon after participate to the Mongol siege of Damascus (1260) as well. The son and successor of the Turkic Zengid ruler Badr al-Din Lu'lu', named Isma'il ibn Lu'lu' (1259–1262), continued in his father's steps and also supported the Mongol troops of Hulagu in the siege of Mayyāfāriqīn with troops and siege engineers.
The horrors of the long siege were recounted by the contemporary Armenian historian Kirakos:
They ate clean and unclean animals and then started to eat people when there was no more food. The strong ate the weak. When the [supply of] poor people was exhausted they turned against one another. Fathers ate sons, and women ate their daughters; and they did not spare the fruit of their wombs. Lovers renounced their loved ones and friends, their acquaintances. And the food supply had so diminished that one litr of human flesh sold for seventy dahekans. Men and food were entirely exhausted, and not just there [in the city], but danger threatened many other districts for those who were besieging the city harassed the land already subjugated by the Tatars with tax collecting and with conveying food and drink for them. Many people died from the extreme cold of the snow which covered the mountains in wintertime.
When the city was captured at last after a siege of two years, the Muslims were massacred, but the Christians were spared. Christian relics were collected and brought back to Armenia, particularly to the Haghpat Monastery.
The Armenian Prince Sevata of Kachen was killed in the conflict. According to the Armenian writer Vartan, he "won the immortal crown, ever faithful to God and to the il-khan; he will share the triumph of those who shared their blood for Christ". Yoshmut was recalled by his father after 10 months.
Finally the Ayyubid ruler Al-Kamil Muhammad was killed when Mayyafariqin fell to the Mongols on 7 April 1260 (23 Rabia II 658).
^ Eastmond, Antony (1 January 2017). Tamta's World: The Life and Encounters of a Medieval Noblewoman from the Middle East to Mongolia. Cambridge University Press. p. 373. doi:10.1017/9781316711774.014. Perhaps the most extreme case came when Armenians, including Avag, his cousin Shahnshah and his vassal Hasan Prosh, were required to besiege Mayyafariqin, the northernmost Ayyubid base in the Jazira before the capture of Akhlat. It took two years to reduce the city, leading to a situation far worse than that faced in Akhlat in 1229–30.
^ Sicker, Martin (30 June 2000). The Islamic World in Ascendancy: From the Arab Conquests to the Siege of Vienna. Bloomsbury Publishing USA. pp. 111–112. ISBN978-0-313-00111-6. A small Mongol detachment, supported by a much larger force of Georgians and Armenians who saw themselves as participating in a crusade against the Muslims under the command of Georgian leader Hasan Brosh, moved against Diyarbekir, which fell after a long siege. While the siege was under way, Hulagu, together with a Christian army from Lesser Armenia, prepared to conquer Musim Syria. (...) He then crossed the Euphrates, and laid siege to Aleppo on January 18, 1260, with the support of Hethum's Armenians and the Frankish troops supplied by Bohemond VI from Antioch. (....) Operating under the Mongol security umbrella, Bohemond also seized the Muslim coastal enclave at Latakia, thereby resestablishing Frankish control of all land between Tripoli and Antioch for the first time since 1187.
^Bai︠a︡rsaĭkhan 2011, pp. 133-134"The Ayyubid ruler of Mayyāfāriqīn and Amida, Al-Kamil Muhammad, had broken his vow to Hűlegű to supply troops for the siege of Baghdad . (...) Hűlegű sent support, in the form of Mongol-Christian troops commanded by a certain Chaghatai and the Armenian Prince Pŕosh Khaghbakian. The Governor of Mosul, Badr al-Dīn Lu’lu’, who was in conflict with al-Kāmil Muhammad, sent a supporting force to the Mongols commanded by his son, along with siege engineers to Mayyāfāriqīn."
^Biran, Michal; Kim, Hodong (31 July 2023). The Cambridge History of the Mongol Empire 2 Volumes. Cambridge University Press. p. 761. ISBN978-1-009-30197-8. Prosh Khaghbakian , together with units of the Cilician army , participated in the siege of the fortress of Mayyāfāriqin in the spring of the same year.
^Bai︠a︡rsaĭkhan, D. (2011). The Mongols and the Armenians (1220-1335). Leiden ; Boston: Brill. p. 133-134. ISBN978-90-04-18635-4. The Ayyubid ruler of Mayyāfāriqīn and Amida, Al-Kamil Muhammad, had broken his vow to Hűlegű to supply troops for the siege of Baghdad . (...) Hűlegű sent support, in the form of Mongol-Christian troops commanded by a certain Chaghatai and the Armenian Prince Pŕosh Khaghbakian. The Governor of Mosul, Badr al-Dīn Lu'lu', who was in conflict with al-Kāmil Muhammad, sent a supporting force to the Mongols commanded by his son, along with siege engineers to Mayyāfāriqīn.
^Eastmond, Antony (1 January 2017). Tamta's World: The Life and Encounters of a Medieval Noblewoman from the Middle East to Mongolia. Cambridge University Press. p. 373. doi:10.1017/9781316711774.014.
^Eastmond, Antony (1 January 2017). Tamta's World: The Life and Encounters of a Medieval Noblewoman from the Middle East to Mongolia. Cambridge University Press. p. 374. doi:10.1017/9781316711774.014. When Mayyafariqin finally fell to the Mongols in 1260 the Armenian troops in the army rushed in to rescue Christian relics.The bones of martyrs of Diocletian's persecutions of the third century had been gathered in the city by its bishop, St Maruta (c. 399–410), giving the city its alternative name of Martyropolis, the 'City of Martyrs'. The soldiers then gave these captured relics to their monasteries. Haghbat managed to acquire the hand of the Apostle St Bartholomew: 'And it really is still there.'
^Muqaras: An Annual on the Visual Culture of the Islamic World, Essays in Honor of J.M. Rogers, eds. Gülru Necipoğlu, Doris Behrens-Abouseif, Anna Contadinia, Koninklijke Brill NV, Leiden 2004, ISSN0732-2992ISBN90 04 139648 vol.21 p.354
^Bai︠a︡rsaĭkhan 2011, p. 137 "Hűlegű demanded that the Georgian King David Ulu support his conquest of Syria and Egypt . Surprisingly, David refused. One might have expected that the Georgian king would have been more than interested in liberating the Holy Land . However, David was not only disinterested in this venture, but also bold enough to refuse Hűlegű’s order. In addition, he sought a revolt, which was suppressed by Arghun Aqa in Southern Georgia in 1260. David Ulu ’s refusal to participate in the Mongol campaign in Syria can be explained by his huge loss of men in the battle for Baghdad."
^Humphreys, R. S. From Saladin to the Mongols, The Ayyubids of Damascus, SUNY Press 1977, pp.348-351