Qazaghan was the chieftain of the Qara'unas tribe in the western Chagatai Khanate. In the 1340s, when Qazan Khan attempted to centralize power and strip the nomadic chiefs of their autonomy, Qazaghan formed a confederation of tribal amirs in rebellion. Despite being wounded in an initial defeat, he rallied his forces and defeated and killed Qazan Khan in 1346, becoming the de facto ruler of Transoxiana.
Knowing that steppe tradition reserved the title of Khan exclusively for descendants of Genghis Khan, Qazaghan refrained from taking the throne himself. Instead, he installed puppet khans of Genghisid blood—first Danishmandji and later Bayan Quli—while ruling with absolute authority under the title of Amir (commander). This power structure served as the direct model for Timur's later regime.
For twelve years Qazaghan maintained effective control, respecting the autonomy of cities like Samarkand while campaigning against the Kart dynasty of Herat and intervening in the Delhi Sultanate. In 1358, he was assassinated by rival tribal leaders during a hunting trip. His death plunged western Transoxiana into renewed fragmentation, paving the way for the rise of his grandson Amir Husayn and the young Timur.