Öljaitü's son, the last Ilkhan Abu Sa'id Bahadur Khan, was enthroned in 1316. He was faced with rebellion in 1318 by the Chagatayids and Qara'unas in Khorasan, and an invasion by the Golden Horde at the same time. Golden Horde khan Özbeg invaded Azerbaijan in 1319 in coordination with Chagatayid prince Yasa'ur who pledged loyalty to Öljaitü earlier but revolted in 1319. Prior to that, he had Amir Yasaul, governor of Mazandaran killed by his subordinate Begtüt. Abu Sa'id was forced to send Amir Husayn Jalayir to face Yasa'ur and while himself marched against Özbeg. Özbeg was defeated shortly thanks to reinforcements by Chupan, while Yasa'ur was killed by Kebek in 1320. A decisive battle was fought on 20 June 1319 near Mianeh with Ilkhanate victory. Under the influence of Chupan, the Ilkhanate made peace with the Chagatais, who helped them crush the Chagatayid revolt, and the Mamluks.