An attempt by Khmer Rouge leader Pol Pot to form a Communist peasant farming society resulted in the deaths of 25 percent of the country's population from starvation, overwork and executions. Vietnam invaded Cambodia in 1978 to help oust Pol Pot's Khmer Rouge regime. The invasion drove the Khmer Rouge forces to the Thai-Cambodian border. Initially the Vietnamese and the Cambodian government laid mines as protection against possible Khmer Rouge guerrilla infiltration. The Khmer Rouge in turn laid them to protect their receding boundary lines. Neither side recorded the locations of the minefields. The result of all this is that the 12 year period between 1979 and 1991 an astonishing ten million antitank and antipersonnel land mines were laid.

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