八思巴
The Ra lineage became particularly important in the Sakya school of Tibetan Buddhism, where it was held by such prominent masters as Sakya Pandita (1182–1251), Drogön Chögyal Phagpa (1235–1280), Butön Rinchen Drup (1290–1364), and Dölpopa Shérap Gyeltsen (1292–1361). The latter two, both of whom also held the Dro lineage, are particularly well known expositors of the "Kālacakra" in Tibet, the practice of which is said to have greatly informed Dölpopa's exposition of "shentong" philosophy. A strong emphasis on "Kālacakra" practice and exposition of the shentong view were the principal distinguishing characteristics of the Jonang school that traces its roots to Dölpopa.