The Śūraṅgama Sūtra (Sanskrit, , Sūtra of the Heroic March) (Taisho no. 945) is a Mahayana Buddhist sutra that has been especially influential on Korean Buddhism (where it remains a major subject of study in Sŏn monasteries) and Chinese Buddhism (where it was a regular part of daily liturgy during the Song). It was particularly important for Zen/Chan Buddhism. The doctrinal outlook of the Śūraṅgama Sūtra is that of Buddha-nature, Yogacara thought, and esoteric Buddhism. The Śūraṅgama Sūtra was widely accepted as a sutra in East Asian Buddhism, where it has traditionally been included as part of Chinese-language Tripitakas. In the modern Taisho Tripitaka, it is placed in the Esoteric Sutra category (密教部). The sutra's Śūraṅgama Mantra is widely recited in China, Korea, Japan and Vietnam as part of temple liturgies. Most modern academic scholars (including Mochizuki Shinko, Paul Demieville, Kim Chin-yol, Lü Cheng 呂澂, Charles Muller and Kogen Mizuno), argue that the sutra is a Chinese apocryphal text that was composed in literary Chinese and reveals uniquely Chinese philosophical concerns. However, some scholars such as Ron Epstein argue that the text is a compilation of Indic materials with extensive editing in China. The sutra was translated into Tibetan during the late eighth to early ninth century and other complete translations exist in Tibetan, Mongolian and Manchu languages (see Translations). Title Śūraṅgama means "heroic valour", "heroic progress", or "heroic march". The Śūraṅgama Sūtra is not to be confused with the similarly titled Śūraṅgama Samadhi Sutra (T. 642 首楞嚴三昧經; Shǒuléngyán Sānmèi Jīng) which was translated by Kumārajīva (344-413). The complete title preserved in , meaning: An alternate translation of the title reads: The title in different languages A common translation of the sutra's name in English is the "Heroic March sutra" (as used e.g. by Matthew Kapstein, Norman Waddell, and Andy Ferguson), or the "scripture of the Heroic Progress" (as used e.g. by Thomas Cleary). The full title of the sutra also appears as: . It is also known by abbreviated versions of the title such as or simply and more commonly . Authorship An original Sanskrit version of Śūraṅgama Sūtra is not known to be extant and the Indic provenance of the text is in question - it is likely to be apocryphal. A Sanskrit language palm leaf manuscript consisting of 226 leaves with 6 leaves missing which according to the introduction "contains the Śūraṅgama Sūtra" was discovered in a