Mainland Southeast Asia

Mainland Southeast Asia, also known as Indochina or the Indochinese Peninsula, is the part of Southeast Asia that is connected to the land. It includes the countries of Cambodia, Laos, Myanmar, Peninsular Malaysia, Singapore, Thailand, and Vietnam. This area is bordered by East Asia to the north, South Asia to the west, and Maritime Southeast Asia to the south and east.

The name "Indochina" came about in the early 1800s and shows how both Indian and Chinese civilizations influenced the culture of this place long ago. Later, it was used for the area called French Indochina, which today is Cambodia, Laos, and Vietnam. Now, people usually say "Mainland Southeast Asia" to talk about this part, instead of the island areas known as Maritime Southeast Asia.

Terminology

People have used different names for the area we now call Mainland Southeast Asia. In old Indian stories, it was called Yāvadvīpa. Another early name was Suvarṇabhūmi, meaning "land of gold," which also might have referred to other parts of Southeast Asia.

The name Indo-China started being used around the early 1800s by European writers who noticed that the area had both Indian and Chinese influences. However, the people living there were from many different groups and spoke many languages. Over time, the name Indochina was used mostly for the area controlled by France. After big changes in the mid-20th century, people began using the name Mainland Southeast Asia more often. Today, that is the common name used for the area, especially in schools and research places.

Biogeography

In biogeography, the Indochinese bioregion is an important area in the Indomalayan realm. It is also a special area for plants in the Oriental Paleotropical Kingdom. This region includes the natural plants and animals from all the countries in Mainland Southeast Asia. Next to it, the Malesian Region covers the Maritime Southeast Asian countries and connects the Indomalayan and Australasian realms.

Main article: Indomalayan realm
Main articles: Maritime Southeast Asia, Australasian realms

Geography

Mainland Southeast Asia is the part of Southeast Asia that is connected to the big land of Asia. It stretches down from Asia and is bordered by India to the west and China to the north. It lies above the equator and has many mountains and lowlands. Important rivers like the Irrawaddy, Chao Phraya, and Mekong flow through this area.

This region is next to Maritime Southeast Asia, which has many islands, separated by seas like the South China Sea. It touches East Asia to the north, South Asia to the west, and Maritime Southeast Asia to the south and east. The Gulf of Thailand is the biggest gulf here, and Tonlé Sap in Cambodia is the largest lake. The Mekong river is the longest in the area, and Hkakabo Razi in Myanmar is the highest mountain.

Climate

The climate changes across Mainland Southeast Asia. Northern areas like parts of Myanmar, Laos, and Vietnam have milder temperatures. Central areas have a tropical savannah climate, while coastal areas experience a tropical monsoon climate. Southern parts, including parts of Thailand, Peninsular Malaysia, and Singapore, have a tropical rainforest climate.

List of states and territories

This list shows all the countries that are part of Mainland Southeast Asia, even if only a small part of them is included. All these countries are members of ASEAN.

* The administrative centre is in Putrajaya.

Economy

Culture

See also: Culture of Southeast Asia

Mainland Southeast Asia is different from the islands of Maritime Southeast Asia because people here live mostly on land, while islanders depend on the sea. The languages spoken here, such as those from the Austroasiatic, Tai–Kadai, and Sino-Tibetan families, share some similarities even though they come from different language groups.

Countries in this area have been shaped by cultures from India and China. For example, Myanmar, Thailand, Laos, and Cambodia feel strong influences from ancient Indian culture, while Vietnam is more linked to Chinese culture but also has some Indian impact.

The region has many religions. Buddhism is common in some places, while others practice Islam, Christianity, or folk religions.

Road traffic drives on the right side in Cambodia, Laos, Myanmar, and Vietnam, but on the left in Malaysia, Singapore, and Thailand.

Demographics

See also: Demographics of Southeast Asia

Mainland Southeast Asia is a place with many different kinds of people, home to over 276 million individuals as of 2025. Big cities in this area have lots of people living close together, especially along the coast in Vietnam. But some parts, like the countryside in Myanmar and Thailand, have fewer people.

The main groups of people here include the Thai, Lao, Viet, Burmese, Khmer, and Malays. There are also many smaller groups, such as Chinese, Indian, and people from various hill tribes. These groups speak different languages, with the Thai and Lao speaking Kra–Dai languages that started in South China. The Khmer and Viet speak Austroasiatic languages, while the Malays speak Austronesian languages. The Burmese language belongs to the Tibeto-Burman family.

As of April 2026, about 277 million people live in Mainland Southeast Asia. This makes up around 5.7% of the population in continental Asia and 3.4% of the entire world population.

Religion

Religion in Mainland Southeast Asia (2020)

1. Buddhism (56.8%)
2. Islam (13.5%)
3. Folk religion (12.7%)
4. Unaffiliated (6.98%)
5. Christianity (6.58%)
6. Hinduism (2.05%)
7. Other (1.44%)

Languages

Major cities

Main article: Cities of Southeast Asia

Some of the biggest cities in Mainland Southeast Asia include:

• Bangkok is the capital of Thailand and has a very large population.
• Ho Chi Minh City is the biggest city in Vietnam.
• Kuala Lumpur is the capital of Malaysia.
• Singapore is a small but crowded city-country.
• Yangon is the largest city in Myanmar.
• Hanoi is another major city and the capital of Vietnam.

Territorial and regional data

Etymology