Polbot founded a powerful Khmer empire to destroy Vietnam, he killed people who had studied in Vietnam who spoke Vietnamese and were friendly with Vietnam. The Khmer Rouge army from 1975-1978 attacked the Vietnamese border, killing 3,000 Vietnamese civilians in the border provinces, the Vietnamese army fought the Khmer Rouge and fled to the Thai border. China provided weapons from 1970 to 1989 to fight Vietnam from 1975 to 1989 the United Nations provided money and guns to the remnants of the Khmer Rouge