Khmer Empire

State · 800–1867 CE · at its largest around 1206 CE

A Southeast Asian empire founded by Jayavarman II and centred on Angkor, whose kings built vast temple complexes including Angkor Wat.

On its lands while it lasted

Champa (c. 192–1832 CE): Collection of Cham polities along the coast of central and southern Vietnam, founded around 192 CE and gradually absorbed by Dai Viet.
Founding of the Khmer Empire (802 CE): Jayavarman II proclaimed himself universal monarch on Phnom Kulen in 802, traditionally marking the foundation of the Khmer Empire.
Koh Ker (c. 922–944 CE): Capital of Khmer Empire (922–944).
Battle of Bach Dang (938) (938 CE): Ngô Quyền defeated a Southern Han fleet using iron-tipped stakes planted in the Bach Dang River, ending a millennium of Chinese rule over northern Vietnam.
Thang Long (Hanoi) (1010 CE): Emperor Lý Thái To moved the capital of Dai Viet to Thang Long in 1010; the city is now Hanoi, capital of Vietnam.
Angkor Wat (c. 1120 CE): Temple complex built in the first half of the 12th century under Suryavarman II, originally dedicated to Vishnu; the largest religious monument in the world.
Jayavarman VII (c. 1122 CE – 1218 CE): Khmer king who drove out the Cham, built Angkor Thom and the Bayon, and made Mahayana Buddhism the state religion.
Sukhothai Kingdom (1238–1438 CE): Early Thai kingdom founded in 1238, regarded in Thai tradition as the cradle of Thai civilisation; it was later absorbed by Ayutthaya.
Ayutthaya (1351–1767 CE): Capital of the Siamese kingdom of Ayutthaya, founded in 1351, which became one of the largest and most cosmopolitan cities in Asia before it was destroyed by Burmese forces in 1767.
Lan Xang (1353–1707 CE): Lao kingdom founded by Fa Ngum in 1353, with its early capital at Luang Prabang; it split into rival kingdoms from 1707.
Luang Prabang (c. 1363 CE): Capital of Lan Xang (1363–1560), Kingdom of Laos (1956–1975).
Phnom Penh (1372 CE): Capital of Kingdom of Cambodia (1956–today), People's Republic of Kampuchea (1979–1989).
Vientiane (1560 CE): Capital of Lan Xang (1560–1707), Kingdom of Laos (1956–1975), Communist Laos (1976–today).
Bangkok (1782 CE): King Rama I founded the Chakri dynasty and moved the Siamese capital to Rattanakosin Island in 1782; Bangkok is now Thailand's capital.
Chulalongkorn (1853 CE – 1910 CE): King Rama V of Siam, who modernised the state, abolished slavery and preserved Siamese independence amid British and French colonial expansion.