The earliest recorded history of Cambodia comes mainly from Chinese sources. They refer to a kingdom called Funan that was established in the first century A.D. in the Mekong valley where the Khmers lived. The ruling class consisted mainly of people who had emigrated from India, bringing with them their customs and religions—Hinduism and Mahayana Buddhism. Hindu beliefs were confined primarily to the ruling class. Buddhism was adopted slowly by the masses. There was much intermarriage between the Khmers and Indians.

Funan was the dominant power in Southeast Asia until the sixth century, when it was overthrown by the Khmer kingdom of Chenla. Chenla, however, soon broke up into two states. Their reunification in 802 marked the beginning of the Khmer Empire, also called Cambodia (from Kambuja, the name of the first Khmer king).

The Khmer Empire, with its capital at Angkor, reached its peak in the 11th and 12th centuries, its territory extending into much of present-day Thailand, Vietnam, and Laos. In the next 200 years, warfare with the Thais, who conquered much Khmer land, and various costly and burdensome building projects weakened the empire. During this time Theravada Buddhism, introduced by the Thais, spread among the people.

By the early 1400's, the Khmers ruled only a small kingdom. Cambodia was reduced to its present size during the 1700's, when it lost additional land to the Thais, and the Mekong delta to the Vietnamese. During the early 1800's, Thais and Vietnamese fought for control of Cambodia.

In 1863 the country, under the nominal rule of its king, became a protectorate of France. In 1887 Cambodia was made a part of the French Indochinese Union. After World War II, the Cambodian king, Norodom Sihanouk, demanded independence for his country, which adopted a constitution in 1947 with internal self-government. Independence was granted in 1953.

In 1955 King Sihanouk abdicated in favor of his father, Norodom Suramarit, and organized a political party. In the 1955 elections, Sihanouk's party won control of the government, and Sihanouk became the dominant political leader. He declared his nation neutral in the struggle between the Communist and anti-Communist countries. When King Suramarit died in 1960, Sihanouk chose not to become king and instead took the title chief of state.

During the Vietnamese War, the Vietcong and North Vietnamese used border areas of Cambodia as a sanctuary. In 1970 Sihanouk was deposed by anti-Communist army leaders. Under the army regime, Cambodian troops moved against the Vietnamese Communists but could not dislodge them. The Vietnamese helped build up a strong Cambodian Communist force called the Khmer Rouge.

In 1975 the Khmer Rouge, led by Pol Pot, emerged victorious and instituted a program of radical social change that destroyed all governmental, educational, and religious institutions. Cities were evacuated and their inhabitants put to work in rural areas. Hundreds of thousands of Cambodians died, killed either by soldiers or as a result of the conditions under which they were forced to work.

A new constitution adopted in 1976 renamed the country Democratic Kampuchea. In 1979 Vietnam overthrew the Pol Pot regime and installed a less repressive government, made up of Khmer Rouge dissidents, which renamed the country the People's Republic of Kampuchea. Soon a rebel coalition consisting of the Khmer Rouge and two non-Communist groups began waging a guerrilla war against the new government. Rebel activity was largely confined to border areas, and in 1989 Vietnam removed its troops. Also in 1989 the country was renamed State of Cambodia.

In 1991 the Cambodian government and the three rebel groups signed a peace treaty and formed a coalition government. The Khmer Rouge withdrew from the coalition in April, 1993, and refused to participate in the May elections. The newly elected National Assembly adopted a constitution creating a monarchy and crowned Norodom Sihanouk king in September. Hun Sen and Prince Ranariddh, Sihanouk's son, were installed as co-premeirs. Hun Sen staged a coup in 1997 and removed Ranariddh from his post. In July, 1998, parliamentary elections were held that were won by Hun Sen, although the results were disputed by the opposition.

Meanwhile, Pol Pot was ousted as leader of the Khmer Rouge in 1997 and put on trial for plotting the murders of political rivals. He died in confinement in 1998. Later that year the last Khmer Rouge leaders officially surrendered, ending 30 years of fighting.