When an ally of the Ü-Tsang ruler threatened destruction of the Gelugpas again, the fifth Dalai Lama Lozang Gyatso pleaded for help from the Mongol prince Güshi Khan (1582–1655), leader of the Khoshut (Qoshot) tribe of the Oirat Mongols, who was then on a pilgrimage to Lhasa. Who did the 5th Dalai Lama beg for help from