(kӘmĕr'), ancient kingdom of SE Asia. In the 6th cent. the Cambodians, or Khmers, established an empire roughly corresponding to modern Cambodia and Laos. Divided during the 8th cent., it was reunited under the rule of Jayavarman II in the early 9th cent.; the capital was established in the area of Angkor by the king Yasovarman I (r. 889–900). The Angkor period (889–1434), the golden age of Khmer civilization, saw the empire at its greatest extent; it held sway over the valleys of the lower Menam (in present-day Thailand) and the lower Mekong (present-day Cambodia and Vietnam), as well as N into Laos.
The Khmer civilization was largely formed by Indian cultural influences. Buddhism flourished side by side with the worship of Shiva and of other Hindu gods, while both religions coalesced with the cult of the deified king. In the Angkor period many Indian scholars, artists, and religious teachers were attracted to the Khmer court, and Sanskrit literature flourished with royal patronage.
The great achievement of the Khmers was in architecture and sculpture. The earliest known Khmer monuments, isolated towers of brick, probably date from the 7th cent. Small temples set on stepped pyramids next appeared. The development of covered galleries led gradually to a great elaboration of plan. Brick was largely abandoned in favor of stone. Khmer architecture reached its height with the construction of Angkor Wat by Suryavarman II (r. 1113–50) and Angkor Thom by Jayavarman VII (r. 1181–c.1218). Sculpture, which also prospered at Angkor, showed a steady development from relative naturalism to a more conventionalized technique. Bas-reliefs, lacking in the earliest monuments, came to overshadow in importance statues in the round; in the later stages of Khmer art hardly a wall was left bare of bas-reliefs, which conveyed in the richness of their detail and vitality a vivid picture of Khmer life.
The Khmers fought repeated wars against the Annamese (see Annam) and the Chams; in the early 12th cent. they invaded Champa, but, in 1177, Angkor was sacked by the Chams. After the founding of Ayuthia (c.1350), Cambodia was subjected to repeated invasions from Thailand, and the Khmer power declined. In 1434, after the Thai captured Angkor, the capital was transferred to Phnom Penh; this event marks the end of the brilliance of the Khmer civilization.