Montagnard is the most common term for a group of at least 20 tribal peoples, whose ancestral lands are in the highlands of Southeast Asia, principally in Vietnam but also in Laos and Cambodia. The term moi has also been used, especially by the French colonial administration, but that is sometimes considered derogatory. Another, more current term is Dega, whose proponents argue is not a French-derived word. 
The individual groups have distinct identities, but warrior traditions are common. They include the Rhade, Meo, Bru, Katu, Tai, Jeh, Hmong, Sedang, Halang, Jarai, M'Nong, and Stieng.  Some sources argue that the Hmong people, while a minority, are not strictly part of this group. 
Under the French
In French Indochina, they maintained some autonomy, and there traditionally was little intermixing or friendship with the lowlanders. The Viet Minh found some quite willing to fight the French,  At the end of the Indochinese revolution, some Frenchmen settled in the hill country.
Under the Diem government
Under the South Vietnamese government of Ngo Dinh Diem, there was a policy to "Vietnamize" them, sometimes forcibly relocating them and giving their land to ethnic Vietnamese. The Communists tried to exploit the resentment against these policies, and reported that the tribesmen, in some cases, hated Diem more than the French.  United States Army Special Forces personnel working with the hill people were often well-received, as distinct from the lowlanders; the Special Forces units tried to work within the tribal tradition. It is not uncommon, when visiting former Special Forces personnel who served in that area, to wear, with great pride, a tribal bracelet or amulet.
In 1964, a number of tribal groups that were working with both U.S. Special Forces and their Army of the Republic of Viet Nam (ARVN) counterparts, the Lac Luong Dac Biet (LLDB), rebelled against the Vietnamese. Montagnard members of Civilian Irregular Defense Groups (CIDG) rebelled at Buon Mi Ga,Buon Sar Pa, Bu Prang, Ban Don, and Buon Brieng, restraining but but not harming USASF, but killing 28 Vietnamese,, then advancing on the town of Ban Me Thuot, the province capital. They remained friendly to the U.S. personnel, and it was only U.S. mediation that calmed the situation. The revolt was under a coalition known as FULRO, which still exists in exile. 
The Hmong people, whose lands are mainly in Laos, formed an anti-communist military force under Vang Pao; this organization received funding through the Central Intelligence Agency. A number of Hmong subsequently resettled in the United States, where cultural acclimation has been difficult.
Under the Socialist Republic of Vietnam
- Friends of the Central Highlands, About the Central Highlands
- Fallah,, Skaidrite Maliks (February 1967), Customs and Taboos of Selected Tribes Residing Along the Western Border of the Republic of Vietnam, Center for Research in Social Systems, American University
- People's Army of Viet Nam ? (captured document) (1965?), VC/NVA Motivation of Ethnic Minorities, MR 6, Combined Document Exploitation Center, pp. 5-6
- People's Army of Viet Nam ? (captured document) (1968), Situation of Ethnic Minority Movements in the Southwestern Highlands, Combined Document Exploitation Center
- McCoy, Alfred W.; Cathleen B. Read & Leonard P., II Adams (1972), The Politics of Heroin in Southeast Asia, Harper Colophon,p. 77-87
- Y-Bler Buonya Scholarship Fund, Montagnard History
- Clymer, Kenton (2006), The War outside Vietnam: Cambodia and Laos, in Wiest, Andrew, Rolling Thunder in a Gentle Land: the Vietnam War Revisited, Osprey Publishing, pp. 105-197
- Sucheng Chan, Hmong Means Free: Life in Laos and America