Chupan attempted to neutralize the influence of the viziers. In 1318, he convinced the discredited former vizier
Rashid-al-Din Hamadani to return to the Ilkhanid court. Rashid, who had many enemies, was accused of poisoning Öljeitü soon after he returned. Chupan promptly turned on him, and Rashid-al-Din was put to death in July of that year. In 1319, armies under the command of the khan of the
Blue Horde,
Öz-Beg, invaded the Ilkhanate. Abu Sa'id led a campaign to stop the invasion. Chupan was on his way to assist Amir Husain (the father of the founder of the
Jalayirids,
Hasan Buzurg) against the raids of the
Chagatai prince
Yasa'ur, who was devastating
Khurasan, but then turned around to support Abu Sa'id upon receiving word that the latter's position across the
Kur River was in danger. Several of Abu Sa'id's officers had deserted, leaving his army weakened. He rushed to his master's position, only to find the troops of the Blue Horde already in flight. Nevertheless, Chupan inflicted heavy casualties upon the enemy. The matter of Abu Sa'id's officers fleeing still needed to be addressed. When the amir enacted punishment against
Qurumushi (also a potential rival), as well as several other officers, for their military negligence, a conspiracy was then launched against him. The conspirators included Abu Sa'id's uncle Irinjin, who Chupan had dismissed from the governorship of
Diyarbakr. Irinjin was defeated near
Mianeh in June 1319. Following these events, Chupan gained almost complete influence over the Ilkhan, and his sons gained prominent positions as the Ilkhanate was parceled out among them. His sons
Timurtash,
Shaikh Mahmud,
Hasan and
Demasq Kaja were given governorships of
Anatolia,
Georgia,
Khorasan and
Azerbaijan respectively. He also married Abu Sa'id's sister
Sati Beg, whom he had been betrothed to since 1316. However, his son Timurtash rose in rebellion in 1322, claiming to be
Mahdi. Chupan went to obtain his surrender personally and even managed to get reappointment to the post by Abu Sa'id. Abu Sa'id sometime fell in love with
Baghdad Khatun, one of emir Chupan's daughters. The emir's efforts to keep Abu Sa'id from marrying his daughter, who was still married to
Hasan Buzurg (another powerful kingmaker of the era), did not help the situation. Abu Said approached Chupan in 1325, claiming her unsuccessfully. Chupan sent his daughter and son-in-law to
Karabakh instead while himself went against
Özbeg and
Tarmashirin who invaded Azerbaijan and Khorasan respectively. Same year Chupan defeated another force led by Özbeg, and even invaded the
Blue Horde. As Chupan had reached the height of his power, he had also sown the seeds of his fall. While Abu Sa'id lacked a treasury, Chupan's son and administrative representative Demasq Kaja spent his wealth extravagantly. This situation annoyed the Ilkhan, who was further influenced against him by his viziers, particularly Rukn al-Din Sa'in, Chupan's own protégé. Chupan's efforts to keep Abu Sa'id from marrying his daughter
Bagdad Katun, who was already married to Hasan Buzurg, did not help the situation. Early in 1326, Chupan led an army to defend against an imminent invasion of
Khurasan. By the request of Abu Said, the
Khagan Yesün Temür awarded his custodian Chupan the nominal title of a chief-commander of all Mongol Khanates. In the autumn of that year, the Chagatai Khan Tarmashirin crossed the
Oxus River, and was defeated by Chupan's son
Hasan near
Ghazna. The vizier Rukn al-Din Sa'in had traveled with Chupan, leaving Demasq Kaja in effective control at the Ilkhanid court. It was at this time that Abu Sa'id decided to make his move. Using opportunity, on 25 August 1327, Abu Sa'id had one of Chupan's sons,
Demasq Kaja, killed, apparently for his activities with a former concubine of Öljaitü's. Hearing this, Chupan marched against Abu Sa'id seeking revenge. he convinced the local religious leader of Simnan, Shaikh 'Ala' al-Daula, to try to negotiate a truce, and then camped near
Qazvin. When the shaikh failed, he continued west, with his troops pillaging on the way. Upon reaching Quha, he was a
day's journey away from Abu Sa'id's camp, but as night fell, most of his army including Muhammad Beg, uncle of Abu Sa'id deserted him near
Ray, taking 30.000 soldier with them, leaving Chupan no choice but to retreat to
Herat. Upon reaching Saveh, he sent his wife Sati Beg back to Abu Sa'id. He then traveled in the direction of
Tabas, with the intention of finding refuge in Transoxiana. Upon reaching the Murghab River, he changed his mind and headed for Khurasan. He was given a friendly welcome into Herat by the local
Kartid ruler, Ghiyath ud-Din. However, he was soon strangled to death under orders of Abu Sa'id in 1327. Chupan and his son Chilaun were both killed. As Chupan's friend, Ghiyath ordered that he be killed by strangulation, which was considered an honorable way to die. The Kartid leader then sent one of Chupan's fingers to Abu Sa'id as proof of the deed. Many of Chupan's sons were to also die in the next few years. His daughter soon forced to divorce Hasan Buzurg and marry Abu Sa'id. In compensation, Hasan was awarded former post of Chupan, rising to be new commander-in-chief of Ilkhanid army. He was buried in
Medina, in the cemetery of
Baqi, under the supervision of his daughter
Bagdad Katun. == Personality ==