Mun or Munism (also called Bongthingism) is the traditional polytheistic, animist, shamanistic, and syncretic religion of the Lepcha people. It predates the seventh century Lepcha conversion to Lamaistic Buddhism, and since that time, the Lepcha have practiced it together with Buddhism. Since the arrival of Christian missionaries in the nineteenth century, Mun traditions have been followed alongside that religion as well. The traditional religion permits incorporation of Buddha and Jesus Christ as deities, depending on household beliefs.
The exonym "Mun" derives from the traditional belief in spirits called mun or mung. Together with bongthing (also bungthing or bóngthíng), mun comprise a central element in the religion. These terms are also used to describe the shaman priesthood that officiates the respective spirits.
The Mun religion and its priesthood are in decline. Conversion to other religions is attributed to economic pressure, as traditional practices are immensely expensive to the ordinary practitioner. It has, however, regained interest among Lepcha as ecological encroachment becomes a growing concern. The environment is so deeply intertwined with Mun beliefs that religious leaders have offered direct opposition to development in areas including the Rathong Chu and Teesta Rivers.
According to Mun mythology, the ancestors of the Lepcha were created by Itbu Rum, who molded them from the pure snows of mount Kangchenjunga. They thus share a lineage with the natural environment and share the cosmos with non-human spirits.
The belief system of Mun is animist, and the natural environment provides much of its basis. Naturally occurring spirits are an object of ceremonial dedication, and they reside in objects such as trees, rocks, and rivers. It is also a syncretic religion that has coexisted with Mahayana Buddhism since its arrival in the seventh century, with practitioners following both religions at the same time. Traditional beliefs may have influenced Lepcha Buddhist scriptures. Modern religious life in a Lepcha village is centered on the gumpa, or Buddhist monastery.
Many Lepcha were converted to Christianity by Scottish missionaries in the 19th century, however Buddhism and the traditional religion have retained important roles in Lepcha religious life. Many Christian Lepcha who have lost their Lepcha language have also distanced themselves from these traditional aspects of Lepcha religion.
Mun religion includes a belief in heaven, called rumlyang or rum lyaang (from rum "god" and lyaang "land/place"). 
Traditional Lepcha beliefs include deities governing family, clan (or lineage, putsho), village, region, and wider levels. Clan deities may be named after mountain peaks or rivers, while regions are home to deities associated with Kangchenjunga such as Chyu-rum-fat. The traditional religion also incorporates Buddha and Jesus Christ as a deities, depending on household beliefs.
Mun spirits are of two general types: the benevolent, or white magician, taung-li mun, and the malevolent, or black magician, mung-sek mun or mung. The latter reside in trees, bushes, rocks, and rivers. The spirits are further subdivided into seven classes: avor mun, pildon mun, angan mun, tungli mun, munjyum mun, mun mook mun and lyang-eet mun. Mun spirits, and witchcraft, are believed to be the invariable culprit of illness.
Ceremonies are usually performed for one or several households, and consist of two parts. The rum portion is an offering to devils. The second, tsandong, is for offerings to the deity Kangchenjunga, to Chyu rum fat, and to the plains. Ceremonies generally seek to appease these spirits. Bongthing rituals generally include prayers, herbs, and amulets, and may also include directed breathing or spitting by the priest. Ritual prayers are sometimes in the form of glossolalia.
Spirit possession occurs in a variety of manners: from a subtle headache to violent, uncontrollable madness. Generally symptoms are the manifestation of mung spirits feeding off the flesh, blood, internal organs, or life energy of the host. Ritual paraphernalia include the ghanta bell, damaru dru necklaces, and consecrated cup filled with chi.
Mun priests are traditionally present at Lepcha celebrations for birth, marriage, and death. Among the Lepcha, Mun officiants are the only obligatory aspect of a commoner's funeral. The funerary ceremony, called dek flee, is accompanied by the sacrifice of a goat and a hen three days after death. It is also performed at the home of people who die elsewhere, for fear of the spirit's return. Auspicious locations and days, particularly in rural settings, may be required of rituals to address more severe ailments or threatening afflictions.
Festivals are also a central aspect of the religion.
The priesthood consists of two types of shaman, corresponding to the spirits they manifest. Mun undergo spirit possession, manifesting supernatural entities bodily, can be male or female. While bongthing are only male, where they have to learn and practice rituals. It is said that Bongthing came before Mun, so as to show respect, the Mun needs to learn both the Bongthing way and the Mun way. Mun undergo spirit possession, manifesting supernatural entities bodily. Their main functions are to ward off misfortunes and illness, perform exorcisms, and guide souls to the afterlife. Some also adjudicate theft cases. Although the priesthood exists, the religion considers true knowledge to be a divine revelation through meditation or dreams, as opposed to a learned talent.
Both the mun and bongthing priesthoods are hereditary, although they do not pass strictly patrilineally. Trained disciples of existing masters are often recruited to service at times of crisis as an election by ancestors or shamanic gods. It is possible for a bongthing to advance to mun status.
Padem are a male hereditary junior priesthood. A padem is usually an initiate on the path to becoming a mun shaman, and has the right to offer sacrifice.
The traditional priesthood also plays a role in the indigenous medical system, as they learn therapeutic knowledge and healing rituals.
- Hamlet Bareh, ed. (2001). "Encyclopaedia of North-East India: Sikkim". Encyclopaedia of North-East India. 7. Mittal Publications: 284–86. ISBN 8170997879.
- Torri, Davide (2010). "10. In the Shadow of the Devil. traditional patterns of Lepcha culture reinterpreted". In Fabrizio Ferrari (ed.). Health and Religious Rituals in South Asia. Taylor & Francis. pp. 149–156. ISBN 1136846298.
- Barbara A. West, ed. (2009). Encyclopedia of the Peoples of Asia and Oceania. Facts on File library of world history. Infobase Publishing. p. 462. ISBN 1438119135.
- Timothy L. Gall, Jeneen Hobby, eds. (2009). Worldmark Encyclopedia of Cultures and Daily Life: Asia and Oceania. 4 (2, revised ed.). Gale. p. 560. ISBN 1414448929.CS1 maint: Uses editors parameter (link)
- Kumar Suresh Singh; Ranju R. Dhamala (1993). Kumar Suresh Singh (ed.). Sikkim. People of India. 39. Anthropological Survey of India, Seagull Books. pp. 99–100. ISBN 8170461200.
- Kaushik, P. K (2007). Sustainable Tribal Culture in India. Pinnacle Technology. p. 17. ISBN 1618202073.
- de Nebesky-Wojkowitz, René (1976). Tibetan Religious Dances: Tibetan Text and Annotated Translation of the ʼChams Yig. Religion and Society. 2. Walter de Gruyter. p. 22. ISBN 902797621X.
- Das, Amal Kumar (1978). The Lepchas of West Bengal. Editions Indian. pp. 12, 193–97.
- Little, Kery (2012). "Sanctity, Environment, and Protest: A Lepcha Tale". In Doma T Bhutia (ed.). Independent People's Tribunal on Dams, Environment and Displacement. Socio Legal Information Cent. pp. 84–93. ISBN 8189479814.
- Plaisier, Heleen (2007). Languages of the Greater Himalayan Region. A Grammar of Lepcha. Languages of the Greater Himalayan region. 5. Brill. pp. 4, 15 (photo). ISBN 9004155252.
- Tamsang, K.P. (1980). The Lepcha-English Encyclopaedic Dictionary. Kalimpong: Mrs. Mayel Clymit Tamzang. p. 746.
- Bisht, Ramesh Chandra. International Encyclopedia of the Himalayas: Bhutan Himalayas. 2. Mittal Publications. p. 106. ISBN 8183242650.
- Suresh Kant Sharma, Usha Sharma, eds. (2005). Sikkim. Discovery of North-East India: Geography, History, Culture, Religion, Politics, Sociology, Science, Education and Economy. 10. Mittal Publications. pp. 325, 326, 329, 332. ISBN 8183240445.CS1 maint: Uses editors parameter (link)
- Gouin, Margaret (2012). Tibetan Rituals of Death: Buddhist Funerary Practices. Routledge Critical Studies in Buddhism. Routledge. p. 253. ISBN 1136959173.
- James F. Fisher, ed. (1978). Himalayan Anthropology: The Indo-Tibetan Interface. World Anthropology. Walter de Gruyter. p. 172. ISBN 3110806495.