Cambodia has also shared the same Buddhist tradition with Thailand and Laos, since the beginning of her modern history. According to the statistics of a year during the 1960s, there were 2,750 monasteries with about 70,000 to 80,000 monks and novices in residence.1 There monks and novices might be either temporary or permanent as they enjoyed the practice of freely entering and leaving the monkhood under the ordination-for-learning tradition which was characteristic also of Thailand and Laos. As in Thailand, there were two denominations or Sub-Orders of the Cambodian Sangha. One was the original order which was later called Mahanikaya to distinguish it from the newly-founded denomination of the Dhammayut. The other, the Dhammayut, was the Sub-Order introduced from Thailand in the last Buddhist century. There were two Patriarchs, one for each of the two denominations.

The Cambodian Sangha appeared to be active in education. Efforts were made to modernize the ecclesiastical education. A Pali High School was founded in Phnom Penh in 2457/1914, which was later transformed into a college. Around the year 2499/1956, arrangements were made for the establishment of the Buddhist University of Phra Sihanu-Raja (The Universite Bouddhique Preah Sihanouk) which began functioning in 2504/1961. The Buddhist Institute of Phnom Penh was also founded to carry out the programmes of propagating Buddhism and Cambodian culture. A Tripitฺaka Board was appointed a few decades ago for the publication of the Canon tohether with its Cambodian translation in 110 volumes. During the 1960s, monks were encouraged to participate in various nation-building programmes. By involving monks in educational and community-welfare projects, it was hoped that the traditional leadership and teaching role of the monks would be strengthened. Primary-school instruction was provided at temple schools throughout the provinces. Monks were engaged in the improvement of village life, leading the peasants in the construction of country roads and bridges and supervising well-digging. Prince Sihanouk was then active in expounding his social gospel of Buddhist Socialism. In the early years of the 1970s, however, political unrest developed in Cambodia, monks and monasteries as well as the people suffered from battles and warfare, and the Buddhist activities were put into obscurity.

In 2498/1955, Prince Narodom Sihanouk abdicated the throne in favour of his father and remained premier to fill a more active political role. When his father died in 2503/1960, Prince Sihanouk, without returning to the throne, became the country's first chief of state. In the face of the Vietnam war, he tried to maintain Cambodia's neutrality. Then, on March 18, 2513/1970, while he was out of the country, his government was overthrown in a pro-Western coup led by Lt.Gen. Lon Nol. Almost suddenly began a long war between the U.S. supplied government troops and the North Vietnamese and Vietcong (gradually replaced, from 2513/1970 to 2516/1973, by the Hanoi-backed native Cambodian Communist insurgents called the Khmer Rouge).

The five-year war ended in April 2518/1975 as the Government surrendered and the Khmer Rouge entered Phnom Penh. Under a new constitution, a State Presidium was established, headed by Pol Pot. Refugees, who escaped to Thailand in thousands, reported that all cities, including Phnom Penh swollen at that time by 2 million refugees, had been evacuated and almost all the inhabitants were forcibly moved to rural areas and put to work in the rice fields or in the jungle where new farm settlements were to be founded. In addition to the long forced marches, they spoke of starvation and wholesale killings. From 2518/1975 through 2521/1978, about 3 or 4 million Cambodians are estimated to have died under the brutality of Pol Pot's regime. The two patriarchs of the two Sub-Orders of the Cambodian Sangha are also reported dead though the causes of their death are still unclear.

In April 2524/1981, a senior Cambodian monk, who is the spiritual leader of several Cambodian communities of refugees in the United States, gave an address in the City Hall of the City of Boston, saying, "... As you know, more than one third of Cambodia's people were killed in the past ten years, including almost all of Cambodia's 80,000 Buddhist monks ...."

In 2521/1978, border clashes with Vietnam developed again. On January 9, 2522/1979, Phnom Penh fell to the Hanoi-backed People's Revolutionary Council of Cambodia headed by Heng Samrin who took over as president of the People's Republic of Kampuchea. Pol Pot forces retreated to the countryside. Fighting still continues, as surely as the increase of the deaths of the Cambodians and the ravage of Cambodia, and will certainly last long as the retreating Democratic Kampuchea government, now with Khieu Samphan replacing Pol Pot as head of state, is prepared to join with all Nationalist forces in a common front to expel the so-called Vietnamese invaders.