During the 1950s, Khmer students in Paris organized their own communist movement, which had little, if any, connection to the hard-pressed party in their homeland. From their ranks came the men and women who returned home and took command of the party apparatus during the 1960s, led an effective insurgency against Sihanouk and Lon Nol from 1968 until 1975, and established the regime of Democratic Kampuchea.

Pol Pot, who rose to the leadership of the communist movement in the 1960s, was born in 1928 (some sources say in 1925) in Kampong Thum Province, north of Phnom Penh. He attended a technical high school in the capital and then went to Paris in 1949 to study radio electronics (other sources say he attended a school for printers and typesetters and also studied civil engineering). Described by one source as a "determined, rather plodding organizer," he failed to obtain a degree, but, according to the Jesuit priest, Father François Ponchaud, he acquired a taste for the classics of French literature as well as for the writings of Marx.

Another member of the Paris student group was Ieng Sary. He was a Chinese-Khmer born in 1930 in South Vietnam. He attended the elite Lycée Sisowath in Phnom Penh before beginning courses in commerce and politics at the Institut d'Etudes Politiques in France. Khieu Samphan, considered "one of the most brilliant intellects of his generation," was born in 1931 and specialized in economics and politics during his time in Paris. In talent he was rivaled by Hou Yuon, born in 1930, who was described as being "of truly astounding physical and intellectual strength," and who studied economics and law. Son Sen, born in 1930, studied education and literature Hu Nim, born in 1932, studied law.

These men were perhaps the most educated leaders in the history of Asian communism. Two of them, Khieu Samphan and Hou Yuon, earned doctorates from the University of Paris Hu Nim obtained his degree from the University of Phnom Penh in 1965. In retrospect, it seems enigmatic that these talented members of the elite, sent to France on government scholarships, could launch the bloodiest and most radical revolution in modern Asian history. Most came from landowner or civil servant families. Pol Pot and Hou Yuon may have been related to the royal family. An older sister of Pol Pot had been a concubine at the court of King Monivong. Three of the Paris group forged a bond that survived years of revolutionary struggle and intraparty strife, Pol Pot and Ieng Sary married Khieu Ponnary and Khieu Thirith (also known as Ieng Thirith), purportedly relatives of Khieu Samphan. These two well-educated women also played a central role in the regime of Democratic Kampuchea.

The intellectual ferment of Paris must have been a dizzying experience for young Khmers fresh from Phnom Penh or the provinces. A number sought refuge in the dogma of orthodox Marxism-Leninism. At some time between 1949 and 1951, Pol Pot and Ieng Sary joined the French Communist Party, the most tightly disciplined and Stalinist of Western Europe's communist movements. In 1951 the two men went toa9e to East Berlin to participate in a youth festival. This experience is considered to have been a turning point in their ideological development. Meeting with Khmers who were fighting with the Viet Minh (and whom they subsequently judged to be too subservient to the Vietnamese), they became convinced that only a tightly disciplined party organization and a readiness for armed struggle could achieve revolution. They transformed the Khmer Students' Association (KSA), to which most of the 200 or so Khmer students in Paris belonged, into a platform for nationalist and leftist ideas. In 1952 Pol Pot, Hou Yuon, Ieng Sary, and other leftists gained notoriety by sending an open letter to Sihanouk calling him the "strangler of infant democracy." A year later, the French authorities closed down the KSA. In 1956, however, Hou Yuon and Khieu Samphan helped to establish a new Marxist-oriented group, the Khmer Students' Union.

The doctoral dissertations written by Hou Yuon and Khieu Samphan express basic themes that were later to become the cornerstones of the policy adopted by Democratic Kampuchea. The central role of the peasants in national development was espoused by Hou Yuon in his 1955 thesis, "The Cambodian Peasants and Their Prospects for Modernization," which challenged the conventional view that urbanization and industrialization are necessary precursors of development. The major argument in Khieu Samphan's 1959 thesis, "Cambodia's Economy and Industrial Development," was that the country had to become self-reliant and had to end its economic dependency on the developed world. In its general contours, Khieu's work reflected the influence of a branch of the "dependency theory" school, which blamed lack of development in the Third World on the economic domination of the industrialized nations.

Data as of December 1987