The Kingdom of Cambodia holds 16.9 million people as of 2023 census data, with Khmer constituting approximately 95.4 percent of the population. This demographic concentration makes Cambodia one of Southeast Asia's most ethnically homogenous nations. The remaining 4.6 percent divides among Vietnamese minority communities estimated between 400,000 and 700,000 persons, Chinese Cambodians numbering roughly 300,000, Cham Muslims at approximately 400,000, and Khmer Loeu highland groups totaling around 200,000 across various tribes. The Bunong people inhabit Mondulkiri Province forests, numbering approximately 40,000. Tampuan communities of roughly 25,000 concentrate in Ratanakiri Province forests. Jarai populations of about 15,000 live near the Vietnamese border. The Kuy people, numbering around 80,000, occupy areas straddling the Thai-Cambodian border in the Dângrêk Mountains. These highland groups maintain distinct languages and animist traditions separate from lowland Khmer Buddhism.
Khmer language belongs to the Austroasiatic family and serves as the sole official language since constitutional reforms in 1993. The script derives from Pallava script of southern India, introduced alongside Sanskrit during the early Khmer Empire period between the sixth and eighth centuries. Modern Khmer contains 33 consonants and 23 vowels in written form, with no spaces between words. French persisted as an administrative language through the protectorate period from 1863 to 1953, and Article 5 of the 1993 constitution designated French as a secondary official language until the 2022 constitutional amendment removed this status. English replaced French as the primary foreign language in education during the 1990s, taught in public schools from grade seven. Chinese language education expanded after 2010 through Confucius Institute programs in Phnom Penh and Siem Reap. Vietnamese remains spoken in households of the Vietnamese minority concentrated in Phnom Penh and along the Mekong River. Cham language survives among Muslim Cham communities in Kampong Cham province, though most Cham now speak Khmer as a primary language.
The Khmer Empire began in 802 when Jayavarman II declared independence from Javanese suzerainty and established himself on Phnom Kulen. He introduced the devaraja cult, positioning the monarch as a divine intermediary. The empire expanded from the Central Plains across present-day Thailand, Laos, and southern Vietnam during the ninth through thirteenth centuries. Suryavarman II commissioned construction of Angkor Wat between 1113 and 1150, dedicating the temple to Vishnu. The structure measures 1,024 meters east to west and 802 meters north to south, with the central tower reaching 65 meters height. Jayavarman VII ruled from 1181 to 1218, converting the empire to Mahayana Buddhism and constructing Angkor Thom, Ta Prohm, and Bayon Temple. The Bayon contains 216 faces carved into 54 towers. Thai armies from Ayutthaya sacked Angkor in 1431, after which Khmer kings relocated the capital southward to Phnom Penh.
French colonial administration formalized through the 1863 treaty signed by King Norodom with Napoleon III. The protectorate initially preserved the monarchy while controlling external affairs and tariffs. French authorities expanded control over internal administration by the 1880s, establishing a résident supérieur with veto power over royal decrees. King Norodom Sihanouk negotiated independence achieved November 9, 1953. He abdicated in 1955 to enter politics directly, forming the Sangkum Reastr Niyum party that won every National Assembly seat in elections from 1955 to 1970. Sihanouk maintained neutrality during early Vietnam War years but permitted North Vietnamese Army use of Cambodian territory along the border. Lon Nol staged a coup March 18, 1970, establishing the Khmer Republic and requesting American military intervention. United States Air Force conducted Operation Menu bombing campaigns from 1969 to 1973, dropping 539,129 tons of ordnance across Cambodian territory according to declassified Defense Department records.
The Khmer Rouge captured Phnom Penh April 17, 1975, under Pol Pot leadership. Forces evacuated the capital's two million residents within three days to agricultural communes. The regime abolished currency, closed schools, banned religious practice, and separated families into labor units. Democratic Kampuchea, as the government named itself, collectivized all agriculture and industry. The Tuol Sleng detention center, designated S-21, processed 14,000 prisoners between 1975 and 1979 according to documentation preserved at the site. Choeung Ek killing field 17 kilometers south of Phnom Penh contains 129 mass graves holding remains of approximately 9,000 persons. The Cambodian genocide research group at Yale University estimates 1.7 to 2.2 million deaths between 1975 and 1979 from execution, starvation, and disease, representing 21 to 24 percent of the 1975 population. Border conflicts with Vietnam escalated through 1978. Vietnamese forces invaded December 25, 1978, capturing Phnom Penh January 7, 1979, and establishing the People's Republic of Kampuchea under Heng Samrin.
Vietnam maintained 170,000 troops in Cambodia through the 1980s while Khmer Rouge forces controlled western border zones. The Paris Peace Accords signed October 23, 1991, established a framework for United Nations Transitional Authority in Cambodia deployment. UNTAC arrived March 1992 with 22,000 military and civilian personnel, the largest UN peacekeeping operation to that date. National elections proceeded May 23-28, 1993, with 89.6 percent voter participation. FUNCINPEC party led by Prince Norodom Ranariddh secured 45.5 percent against 38.2 percent for the Cambodian People's Party. A power-sharing arrangement made Ranariddh first prime minister and Hun Sen second prime minister. This arrangement collapsed in July 1997 fighting in Phnom Penh. Hun Sen has served as prime minister since 1998 elections, transferring the position to his son Hun Manet in August 2023.
King Norodom Sihamoni ascended the throne October 29, 2004, following his father Norodom Sihanouk's abdication. The 1993 constitution established Cambodia as a constitutional monarchy with the king holding ceremonial duties. The monarch serves as head of state but cannot veto legislation or dismiss governments. A nine-member Royal Council of the Throne selects each king from royal bloodlines. National Assembly elections occur every five years through proportional representation, with the most recent held July 23, 2023. The Cambodian People's Party secured 120 of 125 seats.
Buddhism arrived in Cambodia during the early Khmer Empire through Indian traders and missionaries. Theravada Buddhism became the dominant practice by the thirteenth century, replacing earlier Mahayana Buddhism and Hindu worship. The 1993 constitution designates Buddhism as the state religion in Article 43 while guaranteeing freedom of worship. Approximately 97.1 percent of Cambodians practice Theravada Buddhism according to 2019 census data. The sangha contains roughly 70,000 monks across 4,392 wats as of 2020 Ministry of Cults and Religion figures. Muslim Cham communities practice Sunni Islam modified by local custom. The Cham maintained 300 mosques as of 2019. Christianity represents less than 0.5 percent of the population, introduced by French Catholic missionaries during the protectorate.