Güshi Khan
The disappearance of Arslan gave room for the chief of the Khoshut Mongols, Güshi Khan, to act. He had previously visited Tibet as a pilgrim and was attached to the Dalai Lama faction. After Arslan's death he attacked the Chogthu group in Kokonor in concert with the Dzungar chief Baatur Khungtaiji. The Chogthu were completely defeated in 1637, and in the next year Güshi Khan visited the Dalai Lama in Lhasa. Meanwhile, Karma Tenkyong tried to counter Gelugpa influence in the east by allying with Donyo Dorje, the king of Beri in Kham. This ruler supported the Bön religion and was in particular hostile to the Gelugpa, which suffered persecution. A conspiratory letter from Donyo Dorje to Karma Tenkyong was intercepted by a Gelugpa representative. This served as a pretext for Güshi Khan to invade Kham in concert with Parik tribesmen from Amdo. Donyo Dorje was captured and executed in 1640, and in the next year the entire Kham fell under the pro-Gelugpa forces.