 Before Sapaṇ, Sakya was a renowned center for the study of the Lamdre system of the Hevajra Tantra, rooted in the masterful works and reputation of Sachen Kunga Nyingpo. Sapaṇ established Sakya anew as a leader in the study of epistemology. Sapaṇ engaged in many public, spirited debates with members of rival Tibetan schools and, famously, with visiting Brahmanical paṇḍitas (including one *Harinanda), whom he is said to have defeated (see Hugon 2012 on this event). His personal reputation, and the tantric reputation of Sakya, were surely important factors behind the Mongol prince Köden inviting him to negotiate terms for the Tibetan surrender in 1244. It is not entirely clear just what the terms turned out to be, and Sapaṇ died in the Mongol capital. But just a few years later, Sapaṇ’s nephew Phakpa, whom he had brought with him, was named supreme administrator of a united Tibet under Mongol rule—a position that stayed with the Sakya for a century (Wylie 1977 [2003] and Petech 1990).