Southeast Asian Countries: All 11 Nations, Capitals, and ASEAN Overview

Southeast Asia consists of 11 countries: Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, Philippines, Singapore, Thailand, Timor-Leste, and Vietnam. All eleven are members of ASEAN (the Association of Southeast Asian Nations); Timor-Leste, the newest, joined on 26 October 2025. Together these nations are home to more than 680 million people across a region that stretches from mainland river deltas to the world's largest island chains.

All 11 Southeast Asian Countries

The table below lists every country in Southeast Asia, along with its capital, approximate population, land area, and ASEAN membership status. The region is unusual in that all eleven of its nations belong to a single regional bloc, making it one of the most institutionally integrated parts of the developing world.

Where Is Southeast Asia?

Southeast Asia lies between the Indian and Pacific Oceans, positioned south of China and east of India. This crossroads location has shaped the region for millennia: it sits astride some of the world's busiest maritime trade routes, including the Strait of Malacca, through which a large share of global shipping passes. Geographers divide the region into two distinct subregions. Mainland Southeast Asia (historically called Indochina) comprises Myanmar, Thailand, Laos, Cambodia, Vietnam, and Peninsular Malaysia. Maritime Southeast Asia comprises Indonesia, the Philippines, Brunei, Singapore, Timor-Leste, and East Malaysia on the island of Borneo. Altogether the region covers roughly 4.5 million km2.

Mainland Southeast Asia

The mainland is defined by great rivers that flow south from the Tibetan Plateau and the eastern Himalayas. The Mekong River runs about 4,350 km through or along the borders of Myanmar, Laos, Thailand, Cambodia, and Vietnam, making it the lifeline of mainland agriculture. The Irrawaddy shapes the heartland of Myanmar, and the Chao Phraya anchors central Thailand. These rivers deposit nutrient-rich silt to form deltas that rank among the most productive farmland on Earth, which is why Thailand and Vietnam are consistently among the world's top rice exporters. Climates here range from tropical monsoon in the south to subtropical in northern Myanmar and Vietnam, where winters can be cool and even frosty in the highlands.

Maritime Southeast Asia

The maritime portion is a vast scattering of islands set in some of the planet's richest seas. Indonesia alone has more than 17,000 islands spanning three time zones, while the Philippines is made up of 7,641 islands. Because this subregion sits on the Pacific Ring of Fire, it is exposed to frequent earthquakes, volcanic eruptions, and tsunamis. The trade-off is extraordinary fertility, both on land and at sea: the Coral Triangle, centered on maritime Southeast Asia, holds the highest marine biodiversity on Earth, including more reef-fish and coral species than any other region in the world.

ASEAN and Regional Cooperation

The Association of Southeast Asian Nations (ASEAN) was founded on August 8, 1967, by Indonesia, Malaysia, the Philippines, Singapore, and Thailand, the group known as the "ASEAN Five." It has since grown to eleven members, taking in every country in the region; Timor-Leste became the 11th in October 2025. ASEAN promotes economic cooperation, regional stability, and cultural exchange. The ASEAN Economic Community, launched in 2015, aims to build a single market and production base with freer movement of goods, services, investment, and skilled labor. Counted as one economy, ASEAN's combined GDP exceeds $3.6 trillion, which would make it among the largest economies in the world. The bloc also gives smaller members a stronger collective voice on the global stage.

Country Highlights

• Indonesia is the world's largest archipelago, the fourth-most-populous country, and the most populous Muslim-majority nation.
• Philippines ranks among the world's most populous countries, with over 115 million people across 7,641 islands.
• Vietnam has one of Asia's fastest-growing economies, with GDP growth averaging over 6% annually for years.
• Thailand is the only Southeast Asian country never colonized by a European power.
• Singapore is among the wealthiest countries per capita despite covering just 733 km2, transforming from a developing port into a global financial hub within one generation.
• Myanmar moved its capital from Yangon to the purpose-built city of Naypyidaw in 2006.
• Timor-Leste is the region's newest country, gaining full independence from Indonesia in 2002.
• Brunei is one of the wealthiest nations per capita thanks to oil and gas, and is governed as an absolute monarchy.
• Laos is the most heavily bombed country per capita in history, a legacy of the Vietnam War era.
• Cambodia is home to Angkor Wat, the largest religious monument in the world.

Key Facts

• Number of countries: 11, all of them ASEAN members.
• Combined population: over 680 million people.
• Largest country: Indonesia, by both area and population.
• Smallest country: Singapore, at just 733 km2.
• ASEAN combined GDP: more than $3.6 trillion.
• Major river: the Mekong, flowing through six countries.
• Marine biodiversity: includes the Coral Triangle, Earth's richest reef ecosystem.

Fun Facts

• Indonesia has over 17,000 islands, but only about 6,000 are inhabited.
• Thailand was known as Siam until 1939, briefly reverted to Siam in 1945, then became Thailand again in 1949.
• The Philippines was named after King Philip II of Spain in the 16th century.
• Vietnam's Ha Long Bay contains roughly 1,600 limestone islands and islets.
• Singapore's Changi Airport has been voted the world's best airport more than ten times.

Frequently Asked Questions

How many countries are in Southeast Asia?

There are 11 countries in Southeast Asia: Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand, Timor-Leste, and Vietnam. All eleven belong to ASEAN, Timor-Leste having joined in October 2025.

What is the difference between ASEAN and Southeast Asia?

Southeast Asia is a geographic region of 11 countries, while ASEAN is a political and economic organization that, since Timor-Leste joined in October 2025, includes all 11 of them. The difference is now one of kind rather than membership: ASEAN is a treaty organisation, and Southeast Asia is a place.

Which is the largest and which is the smallest Southeast Asian country?

Indonesia is by far the largest, covering more than 1.9 million km2 and home to about 275 million people. Singapore is the smallest by area at just 733 km2, although Brunei and Timor-Leste have smaller populations.

Was any Southeast Asian country never colonized?

Yes. Thailand is the only country in the region that was never colonized by a European power, serving historically as a buffer state between British-controlled Burma and Malaya and French Indochina.