The Khoits ranked lower within the Oirat tribal hierarchy — their taishi answered to the Dorbet Oirats — and by the time Amursana became khan, the power of the Dzungars was on the wane.
The death of Tsewang Rabtan's son Galdan Tseren and the succession of Tsewang Dorji Namjal in 1745 led to a fierce internecine struggle for Dzungar leadership.
Tsewang Dorji was subsequently blinded and imprisoned in Aksu by his elder brother Lama Dorji (喇嘛達爾札; d. 1752), who then usurped the khanship.
Although a Khoit, Lama Dorji's only opposition came from the Dzungar Khan, Dawachi, grandson of Khong Tayiji Tsewang Rabtan's cousin Tsering Dhondup (大策凌敦多布).
In 1751, Lama Dorji defeated Dawachi who was forced to flee across the border into Kazakh Khanate territory with about a dozen men.
Amursana was one of Dawachi's few followers who returned to Tarbagatai to join up with his Khoit clansmen.
With a thousand of his men, he then marched to Ili where they surprised Lama Dorji and killed him on 13 January 1752.
Other sources claim that Lama Dorji was killed by his own troops in December 1752.
Dawachi then assumed the title 'of 'taisha of the Dzungars and richly rewarded Amursana for his efforts.

As a Khoit, Amursana did not rank as part of the Dzungar Khanate's hierarchy and relied on Dawachi for influence among the various Oirat clans.
Nevertheless, marriage to the daughter of Ablai Khan, leader of the neighboring Kazakh Khanate, and alliances with various Oirat clan leaders enabled him to build up enough support to call on Dawachi to divide the Khanate's lands between them.
Dawachi refused and instead attacked his former ally, forcing him to flee east to Khovd.
There, Amursana swore allegiance to the Qing Qianlong Emperor, bringing with him 5,000 soldiers and 20,000 women and children.
He then traveled to Beijing to seek the emperor's assistance in defeating Dawachi and retaking Ili and neighboring Kashgar.
Amursana's persuaded the ambitious and glory-seeking Qianlong to back his plan, in addition to granting him a princedom of the first degree (雙親王; 双亲王), which entitled Amursana to double stipends and privileges, as a bonus.

Meanwhile, most of the Oirat Khoshut had also defected to the Qing leaving Dawachi—reportedly a "drunken and incompetent" ruler—with only the Dzungars under his control.
The Khoits ranked lower within the Oirat tribal hierarchy — their taishi answered to the Dorbet Oirats — and by the time Amursana became khan, the power of the Dzungars was on the wane. The death of Tsewang Rabtan's son Galdan Tseren and the succession of Tsewang Dorji Namjal in 1745 led to a fierce internecine struggle for Dzungar leadership. Tsewang Dorji was subsequently blinded and imprisoned in Aksu by his elder brother Lama Dorji (喇嘛達爾札; d. 1752), who then usurped the khanship. Although a Khoit, Lama Dorji's only opposition came from the Dzungar Khan, Dawachi, grandson of Khong Tayiji Tsewang Rabtan's cousin Tsering Dhondup (大策凌敦多布). In 1751, Lama Dorji defeated Dawachi who was forced to flee across the border into Kazakh Khanate territory with about a dozen men. Amursana was one of Dawachi's few followers who returned to Tarbagatai to join up with his Khoit clansmen. With a thousand of his men, he then marched to Ili where they surprised Lama Dorji and killed him on 13 January 1752. Other sources claim that Lama Dorji was killed by his own troops in December 1752. Dawachi then assumed the title 'of 'taisha of the Dzungars and richly rewarded Amursana for his efforts.
As a Khoit, Amursana did not rank as part of the Dzungar Khanate's hierarchy and relied on Dawachi for influence among the various Oirat clans. Nevertheless, marriage to the daughter of Ablai Khan, leader of the neighboring Kazakh Khanate, and alliances with various Oirat clan leaders enabled him to build up enough support to call on Dawachi to divide the Khanate's lands between them. Dawachi refused and instead attacked his former ally, forcing him to flee east to Khovd. There, Amursana swore allegiance to the Qing Qianlong Emperor, bringing with him 5,000 soldiers and 20,000 women and children. He then traveled to Beijing to seek the emperor's assistance in defeating Dawachi and retaking Ili and neighboring Kashgar. Amursana's persuaded the ambitious and glory-seeking Qianlong to back his plan, in addition to granting him a princedom of the first degree (雙親王; 双亲王), which entitled Amursana to double stipends and privileges, as a bonus.
Meanwhile, most of the Oirat Khoshut had also defected to the Qing leaving Dawachi—reportedly a "drunken and incompetent" ruler—with only the Dzungars under his control.
Amursana