Reign of Arpa Ke'un Following the death of Abu Said in 1335, several parties competed for the Ilkhanid throne. Hasan stood neutral throughout the reign of
Arpa, he became supreme commander of Ilkhanate armies.
Reign of Muhammad After defeat of Arpa by
Ali Padshah on 29 April 1336 and subsequent murder on 15 May 1336, Hasan Buzurg saw his chance and raised a child,
Pir Husayn from
Tabriz, a great-grandson of
Möngke Temür, to claim the position in alliance with Hajji Taghay, the
Sutaid claimant to
Diyar Bakr in opposition to Ali Padshah. Pir Husayn was crowned in
Anatolia on 20 July 1336 with the title "Muhammad Khan" and Hasan left for Iran, leaving his deputy
Eretna behind to act as governor. Later on 24 July Hasan Buzurg and Muhammad met the forces of Musa Khan and 'Ali Padshah in
Battle of Qara Darra, near Ala-Tagh area; Musa was defeated and 'Ali Padshah killed. Hasan Buzurg pursued Musa on his way to
Baghdad and created many losses for his enemy. He then proceeded to
Tabriz where he put Muhammad on throne and married the granddaughter of Chupan and the wife of Abu Sa'id,
Dilshad Khatun, who was pregnant with Abu Sa'id's daughter. Meanwhile, the amirs in
Khurasan adopted their own candidate for Ilkhan,
Togha Temür. Togha set off in 1337 to subdue western Persia. Azarbaijan and 'Iraq-i 'Ajam were taken. In March he arrived before Sultaniyeh, the former capital of the Ilkhans, and Hasan Buzurg withdrew to
Arran. Musa's forces, initially battling Togha's, now joined the invader. Togha and Musa met Hasan Buzurg at Soghurlug in the Maragheh area on 15 June 1337; Hasan defeated them, took Musa and Togha Temür's emir Shaykh Ali prisoner shortly after, and executed them on 10 July 1337. Togha gave up the campaign and withdrew to eastern Persia. With Muhammad's and Hasan's position solidified,
Eretna was appointed governor of Anatolia. Hasan spent the winter of 1338 in
Mughan. The conflict with the Chobanids again boiled over, and Hasan Buzurg and Jahan Temur met Hassan Kuchak and his new puppet
Suleiman Khan in battle on the Jaghatu. There Hasan Buzurg was defeated on June 26, 1340. He fled to Baghdad; following which he deposed Jahan Temür. With the Chobanids continuing to press him, Hasan Buzurg this time turned to
Mamluk Sultanate. He promised Baghdad and Diyar Bakr in return of Mamluk military assistance and capture of Azerbaijan for himself. In 1341,
Sutayid Barhashin (son of Hajji Taghay) and Ibrahimshah (nephew of Hajji Taghay) was sent to
Aleppo, court of
al-Nasir as emissaries. The alliance was a success at first but was later broken thanks to cunning of Hasan Kuchek, who instructed
Artuqid ruler of
Mardin al-Malik as-Salih to write a letter to Mamluk sultan on alleged Jalayirid truce with Chobanids, advising not to aid Hasan Buzurg. In return, al-Malik was promised that his son-in-law Ibrahim Shah
Sutayid would be granted Diyar Bakr instead of pro-Jalayirid Hajji Taghay. , and contribution from the line of
Genghis Khan. Hasan Buzurg for some time again recognized Togha Temur's suzerainty, and struck coins in his name. After he stopped recognizing Togha in 1344, he still did not proclaim himself independent, and ruled with the title of
ulus beg, as a mere governor, simply leaving the Ilkhan throne unfilled. Nevertheless, this marks the beginning of effectively independent Jalayirid rule. For the rest of his reign, Hasan Buzurg attempted to deal with the Chobanids. He managed to form an alliance with Hassan Kuchak's uncle Surgan, as well as the governor of
Diyarbakır and the
Mamluk Sultanate, but Surgan was soon convinced to abandon the alliance, and the Mamelukes withdrew shortly after. He also offered assistance to another of Hassan Kuchak's uncles,
Yagi Basti, as well as to Mas’ud Shah of the
Injuids, in their attempt to expel Hassan Kuchak's cousin
Pir Hosayn from
Shiraz. The murder of Hassan Kuchak in 1343 did not provide much relief, for his brother
Malek Ashraf sent an army to conquer Baghdad in 1347. Jalayirid forces, however, inflicted heavy losses on the force, which was forced to retreat by the summer. While Malek Ashraf and the Chobanids would survive until 1357, their threat to the Jalayirids was diminished. Hasan Buzurg continued to play an influential part in Persian politics; he assisted the Injuid Abu Ishaq against the
Muzaffarids, helping him restore his rule in
Isfahan in 1353. The latter, however, destroyed the Injuids in 1357. Hasan Buzurg died in July 1356 and was buried in
Najaf. He was succeeded by his son,
Shaikh Awais Jalayir. == Family ==