Mainland Southeast Asia (historically known as Indochina and the Indochinese Peninsula) is the continental portion of Southeast Asia. It comprises the countries of Cambodia, Laos, Myanmar, Peninsular Malaysia, Singapore, Thailand and Vietnam. MSEA borders East Asia to the north, South Asia to the west, and Maritime Southeast Asia to the south and east.
The term Indochina (originally Indo-China) was coined in the early nineteenth century, emphasizing the historical cultural influence of Indian and Chinese civilizations on the region. The term was later adopted as the name of the colony of French Indochina (present-day Cambodia, Laos, and Vietnam). Today, the term "Mainland Southeast Asia" is more commonly used, in contrast to Maritime Southeast Asia for the island groups off the coast of the continental region.
Terminology
thumb|1886 map of Indochina, from the [[Scottish Geographical Magazine]]
In Indian sources, the earliest name connected with Southeast Asia is . Another possible early name of mainland Southeast Asia was ('land of gold'), a toponym, that appears in many ancient Indian literary sources and Buddhist texts, but which, along with ('island' or 'peninsula of gold'), The unfamiliar outsiders from Europe thought the region had a dual Indian and Chinese cultural makeup. Much of the mainland practiced Theravada Buddhism while the east coast had a Confucian Kingdom (Đại Việt) with a language based on Chinese characters. Nevertheless, Indo-China had already gained traction and soon supplanted alternative terms such as Further India and the Peninsula beyond the Ganges. Later, however, as the French established the colony of French Indochina (covering present-day Cambodia, Laos, and Vietnam), use of the term became more restricted to the French colony.
Biogeography
In biogeography, the Indochinese bioregion is a major region in the Indomalayan realm, and also a phytogeographical floristic region in the Oriental Paleotropical Kingdom. It includes the native flora and fauna of all the countries above. The adjacent Malesian Region covers the Maritime Southeast Asian countries, and straddles the Indomalayan and Australasian realms.
Geography
thumb|right|[[Mekong River]]
thumb|Topographic Map of Mainland Southeast Asia 2005
Mainland Southeast Asia is formally classified as a continental region which extends from the Asian landmass. It is fundamentally a "continental projection" of Asia, It has a mean depth of 45 meters, and a maximum depth of 80 meters.
Tonlé Sap in Cambodia is the largest freshwater lake in Southeast Asia with a maximum surface area of .
The Mekong is 4,900 km long and the longest river in Southeast Asia. It flows from its source in the Tibetan Plateau through multiple countries in MSEA including Myanmar, Laos, Thailand, Cambodia, and Vietnam.
Climate
thumb|Climate of Southeast Asia
The Köppen climate classification says the northern areas of Myanmar, Laos and Vietnam have a temperate climate. Central Myanmar, Thailand, Cambodia, Southern Laos have mainly a tropical savannah climate. The western coastline along the Bay of Bengal, Andaman Sea and Southern Thailand have a tropical monsoon climate. Central and Southern Vietnam have both tropical savannah and monsoon climates. The tip of Southern Thailand, Peninsular Malaysia and Singapore have a tropical rainforest climate.
List of states and territories
thumb|A political map of Mainland Southeast Asia
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{| class="sortable wikitable" style="text-align:right;"
|-
!Arms
!Flag
! scope="col" | Name
! scope="col" data-sort-type="number" | Area<br />()
! scope="col" | Population<br />(2025)
! scope="col" | Population density<br />()
! scope="col" | HDI<br />(2021)
! scope="col" | Capital
|-
!
!
! scope="row" style="text-align:left;" | Cambodia
| 181,035
| 17,577,760
|
| 0.593
| style="text-align:left;" | Phnom Penh
|-
!
!
! scope="row" style="text-align:left;" | Laos
| 236,800
| 7,647,000
|
| 0.607
| style="text-align:left;" | Vientiane
|-
!
!
! scope="row" style="text-align:left;" | Malaysia
| 132,090 (peninsular portion only)
| 27,111,506 (79.2% in peninsular portion)
|
| 0.803
| style="text-align:left;" | Kuala Lumpur *
|-
!
!
! scope="row" style="text-align:left;" | Myanmar
| 676,578
| 51,316,756
|
| 0.585
| style="text-align:left;" | Nay Pyi Taw
|-
!
!
! scope="row" style="text-align:left;" | Singapore
| 719.2
| 6,110,200
|
| 0.939
| scope="row" style="text-align:left;" | Singapore
|-
!
!
! scope="row" style="text-align:left;" | Thailand
| 513,120
| 65,859,640
|
| 0.800
| style="text-align:left;" | Bangkok
|-
!
!
! scope="row" style="text-align:left;" | Vietnam
| 331,210
| 101,343,800
|
| 0.703
| style="text-align:left;" | Hanoi
|-
!Total
!
! style="text-align: left;" |
|2,071,552.2
|276,966,662
|133.7
|0.718
| style="text-align: left;" |
|}
Economy
{| class="wikitable sortable"
!Country
!Currency
!Population
(2020)
!Nominal GDP
(2020) $ billion
!GDP per capita
(2020)
!GDP growth
(2020)
!Inflation
(2020)
!Main industries
|-
|
|៛ Riel US$ US Dollar
| style="text-align:right" |16,718,965
| style="text-align:right" |$26.316
| style="text-align:right" |$1,572
| style="text-align:right" | -2.8%
| style="text-align:right" |2.5%
|Clothing, gold, agriculture
|-
|
|₭ Kip
| style="text-align:right" |7,275,560
| style="text-align:right" |$18.653
| style="text-align:right" |$2,567
| style="text-align:right" |0.2%
| style="text-align:right" |6.5%
|Copper, electronics, Tin
|-
|
|RM Ringgit
| style="text-align:right" |32,365,999
| style="text-align:right" |$336.330
| style="text-align:right" |$10,192
| style="text-align:right" | -6%
| style="text-align:right" | -1.1%
|Electronics, petroleum, petrochemicals, palm oil, automotive
|-
|
|K Kyat
| style="text-align:right" |54,409,800
| style="text-align:right" |$70.890
| style="text-align:right" |$1,333
| style="text-align:right" |2%
| style="text-align:right" |6.1%
|Natural gas, agriculture, clothing
|-
|
|S$ Singapore dollar
| style="text-align:right" |5,850,342
| style="text-align:right" |$337.451
| style="text-align:right" |$58,484
| style="text-align:right" | -6%
| style="text-align:right" | -0.4%
|Electronics, petroleum, chemicals
|-
|
|฿ Baht
| style="text-align:right" |69,799,978
| style="text-align:right" |$509.200
| style="text-align:right" |$7,295
| style="text-align:right" | -7.1%
| style="text-align:right" | -0.4%
|Electronics, automotive, rubber
|-
|
|₫ Đồng
| style="text-align:right" |97,338,579
| style="text-align:right" |$340.602
| style="text-align:right" |$3,498
| style="text-align:right" |2.9%
| style="text-align:right" |3.8%
|Electronics, clothing, petroleum
|}
Culture
thumb|right|190px|[[Ethnic groups in Southeast Asia|Ethnolinguistic groups of mainland Southeast Asia]]
Mainland Southeast Asia contrasts with Maritime Southeast Asia, mainly through the division of largely land-based lifestyles in Indochina and the sea-based lifestyles of the Indonesian archipelago and Philippine archipelago, as well as the dividing line between the Austroasiatic, Tai–Kadai, and Sino-Tibetan languages (spoken in Mainland Southeast Asia) versus the Austronesian languages (spoken in Maritime Southeast Asia). The languages of the mainland form the Mainland Southeast Asia linguistic area: although belonging to several independent language families, they have converged over the course of history and share a number of typological similarities.
The countries of Mainland Southeast Asia received cultural influence from both India and China to varying degrees. Myanmar, Thailand, Laos, and Cambodia were all significantly influenced by the ancient cultures of India and Sri Lanka. Vietnam is generally considered part of the Sinosphere, although it has also been influenced to a lesser extent by India. The former kingdom of Champa in Central and Southern Vietnam was very influenced by Indian culture.
Overall, Mainland Southeast Asia is religiously diverse, with Buddhism forming a majority religion in parts of the region, alongside significant Muslim, Christian, and folk religious traditions.
The direction of road traffic is on the right side in Cambodia, Laos, Myanmar and Vietnam. It is on the left side in Malaysia, Singapore and Thailand.
Demographics
Mainland Southeast Asia is an ethnically diverse region with over 276 million people (2025). The metropolitan areas are densely populated. The capital cities are also economic hubs. However, the countryside of Myanmar and Thailand are sparsely populated. Cambodia and Laos have low density populations. The coastline of Vietnam is densely populated.
The biggest ethnic groups include the Thai, Lao, Viet, Burmese, Khmer and Malays. There are hundreds of other minor ethnic groups including Chinese, Indian, and various indigenous hill tribe populations. The Thai and Lao speak Kra–Dai languages which originate from South China. The Khmer and Viet speak Austroasiatic languages, but the Malays are Austronesian. The Burmese language is Tibeto-Burman.
As of April 2026, MSEA's population of around 277 million people represents 5.7% of the population in continental Asia and 3.4% of the total world population.
Religion
{| class="wikitable"
! width="175" |Country
!Religions
|-
|
|Buddhism (97%), Islam, Christianity, Animism, others
|-
|
|Buddhism (67%), Animism, Christianity, others
|-
|
|Islam (61.3%), Buddhism, Christianity, Hinduism, Animism
|-
|
|Buddhism (89%), Islam, Christianity, Hinduism, Animism, others
|-
|
|Buddhism (31.1%), Christianity (18.9%), Islam (15.6%), Taoism (8.8%), Hinduism (5%), others (20.6%)
|-
|
|Buddhism (93.5%), Islam (5.4%), Christianity (1.13%), Hinduism (0.02%), others (0.003%)
|-
|
|Vietnamese folk religion (45.3%), Buddhism (16.4%), Christianity (8.2%), Other (0.4%), Unaffiliated (29.6%)
|}
Languages
{| class="wikitable"
!Country/Region
!Languages
|-
|
|Khmer, English, French, Teochew, Vietnamese, Cham, Mandarin, others
|-
|
|Lao, French, Thai, Vietnamese, Khmu, Hmong, Phuthai, Bru, Tai Lü, Akha, Iu Mien and others
|-
|
|Malaysian, English, Mandarin, Tamil, Daro-Matu, Kedah Malay, Sabah Malay, Brunei Malay, Kelantan Malay, Pahang Malay, Acehnese, Javanese, Minangkabau, Banjar, Buginese, Tagalog, Hakka, Cantonese, Hokkien, Teochew, Fuzhounese, Telugu, Bengali, Punjabi, Sinhala, Malayalam, Arabic, Brunei Bisaya, Okolod, Kota Marudu Talantang, Kelabit, Lotud, Terengganu Malay, Semelai, Thai, Iban, Kadazan, Dusun, Kristang, Bajau, Jakun, Mah Meri, Batek, Melanau, Semai, Temuan, Lun Bawang, Temiar, Penan, Tausug, Iranun, Lundayeh/Lun Bawang, and others see: Languages of Malaysia
|-
|
|Burmese, Shan, Kayin (Karen), Rakhine, Kachin, Chin, Mon, Kayah, Mandarin, Bengali, Tamil, Telugu and other ethnic languages.
|-
|
|English, Malay, Mandarin Chinese, Tamil, Hokkien, Teochew, Cantonese, Hakka, Japanese, Telugu, Malayalam, Punjabi, Indonesian, Boyanese, Buginese, Javanese, Balinese, Singlish creole and others
see: Languages of Singapore
|-
|
|Thai, Isan, Northern Khmer, Malay, Karen, Hmong, Teochew, Minnan, Hakka, Yuehai, Burmese, Iu Mien, Tamil, Bengali, Urdu, Arabic, Shan, Tai Lü, Phuthai, Mon and others
|-
|
|Vietnamese, Cantonese, Khmer, Hmong, Tày, Cham and others
|}
Major cities
<gallery mode="packed" style="text-align: center;" heights="110" perrow="3">
File:0008871 - Krung Thep Bridge 001.jpg|Bangkok is the capital of Thailand and has one of the world's largest metropolitan populations.
File:Saigon skyline night view.jpg|Ho Chi Minh City is the most populous municipality of Vietnam.
File:Moonrise over kuala lumpur.jpg|Kuala Lumpur is the capital of Malaysia.
File:Singapore skyline at sunset viewed from Gardens by the Bay East - 20120426.jpg|Singapore is a densely populated city-state.
File:City Lay-down under the Fullmoon.jpg|Yangon is the largest city in Myanmar.
File:Hanoi Cityscape.jpg|Hanoi is the capital of Vietnam.
</gallery>
Territorial and regional data
Etymology
{| class="wikitable"
! rowspan="2" |Flag
! colspan="2" |Common Name
! colspan="2" |Official name
! colspan="4" |ISO 3166 Country Codes
|-
!Exonym
!Endonym
!Exonym
!Endonym
!ISO Short Name
!Alpha-2 Code
!Alpha-3 Code
!Numeric
|-
|
|Cambodia
| align="center" |កម្ពុជា
|Kingdom of Cambodia
|ព្រះរាជាណាចក្រកម្ពុជា
|Cambodia
|KH
|KHM
|116
|-
|
|Laos
| align="center" |ປະເທດລາວ
|Lao People's Democratic Republic
|ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ
|Lao People's Democratic Republic (the)
|LA
|LAO
|418
|-
|
|Malaysia
| align="center" |Malaysia
|Malaysia
|Malaysia
|Malaysia
|MY
|MYS
|458
|-
|
|Myanmar
| align="center" |မြန်မာနိုင်ငံ
|Republic of the Union of Myanmar
|ပြည်ထောင်စုသမ္မတမြန်မာနိုင်ငံတော်
|Myanmar
|MM
|MMR
|104
|-
|
|Singapore
| align="center" |Singapore
|Republic of Singapore
|Republic of Singapore
|Singapore
|SG
|SGP
|702
|-
|
|Thailand
| align="center" |ประเทศไทย
|Kingdom of Thailand
|ราชอาณาจักรไทย
|Thailand
|TH
|THA
|764
|-
|
|Vietnam
| align="center" |Việt Nam
|Socialist Republic of Viet Nam
|Cộng hòa Xã hội chủ nghĩa Việt Nam
|Viet Nam
|VN
|VNM
|704
|}
See also
- Southeast Asia
- Maritime Southeast Asia
- Western Southeast Asia
- East Indies
; Related regional concepts
- Mainland Southeast Asia linguistic area
- Southeast Asian Massif
- Sundaland
- Zomia
; Sub-regions
- Golden Chersonese
- Golden Triangle
- Greater Mekong Subregion
Notes
References
Further reading
- History of the mountain people of southern Indochina up to 1945 (Bernard Bourotte, i.e. Jacques Méry), U.S. Agency for International Development, 195? (PDF)