The Six Gatekeeper Paṇḍitas (mkhas pa sgo drug) are, according to Tāranātha (1575–1635), preeminent scholars of Vikramaśīla around the 10–11th century, i.e., Ratnākaraśānti, Vāgīśvarakīrti, Prajñākaramati, Nāropa, Ratnavajra, and Jñānaśrīmitra. The notion is found in a number of Tibetan historical sources. The present paper aims to clarify two points: (1) Does the notion “Six Gatekeeper Paṇḍitas” have an Indic origin? (2) Which text first referred to the notion? In order to clarify point (1), I investigated five categories: whether the notion was known by (a) the Paṇḍitas themselves, (b) their direct disciples, (c) Tibetan contemporaries, (d) later Indic traditions, or (e) later Tibetan traditions. Among them, (b) and (c) are testified to by the colophon of Ratnākaraśānti’s Madhyamakālaṃkāropadeśa (D no. 4085), which refers to Ratnākaraśānti as the foremost of sgo srung chen po bzhi (probably a notion preceding mkhas pa sgo drug) and that of Prajñākaramati’s Abhisamayālaṃkāravṛttipiṇḍārtha (D no. 3795), which mentions Prajñākaramati as nub kyi sgo glegs. These expressions in the colophons are of the 11th century, in case they are not later additions. As for point (2), one of the earliest sources is ’Brog mi’s biography in the Chos ’byung me tog snying po sbrang rtsi’i bcud of Nyang ral Nyi ma’i ’od zer (ca. 1124–1192). ’Brog mi’s biography written by Grags pa rgyal mtshan, which is probably even earlier than Nyang ral’s version, does not mention mkhas pa sgo drug, and almost all other later biographies of ’Brog mi’s refer to the notion. This suggests that Nyang ral’s version is the one of the earliest that mentions this notion among ’Brog mi’s biographies.
