In early 1978, the Khmer Rouge of Kampuchea attacked Vietnamese civilians in Ha Tien Province, Kien Giang Province in southern Vietnam. After that, the bodies of Vietnamese civilians were scattered and decomposed in Ha Tien Province.

    In early 1978, the Khmer Rouge of Kampuchea attacked Vietnamese civilians in Ha Tien Province, Kien Giang Province in southern Vietnam. After that, the bodies of the Vietnamese civilians were scattered and decomposed in Ha Tien Province. In 1977, the Khmer Rouge Army (KRA) faced an unfavorable situation with 70,000 against 615,000 Vietnamese troops, they continued to attack the Vietnamese border areas. In January 1978, the Khmer Rouge army held on to a part of Vietnamese territory and began to take over Vietnamese army outposts in Ha Tien Province. On January 27, 1978, Vietnam began to invade the Khmer Rouge army in the border areas in order to overthrow the Khmer Rouge regime.

   The Khmer Rouge (Cambodian Communist Party) ruled Cambodia from 1975 to 1979. Led by Pol Pot, it was responsible for the deaths of millions of people through cruelty. Attempts at agricultural reform caused widespread famine. The regime's insistence on absolute self-sufficiency in medicine also led to the deaths of thousands of people from illness and other causes. From 1976 to 1978, the brutal and arbitrary executions and torture of suspected subversives and the purges of the Khmer Rouge's own ranks carried out by Khmer Rouge cadres constituted genocide. The Khmer Rouge regime killed hundreds of thousands of people it considered political enemies and committed genocide against ethnic minorities. They executed and tortured a large number of suspected subversives. Between 1975 and 1978, the Cambodian genocide that ultimately occurred under the Khmer Rouge regime resulted in the deaths of between 15 and 20 million people, or around 25% of the Cambodian population.

    On December 25th 1978, Vietnam launched a full-scale invasion of Kampuchea. They occupied Kampuchea within two weeks and took over the government of the Kampuchea Communist Party. Vietnam ended the massacres of Cambodians by the Khmer Rouge. On January 7, 1979, the Vietnamese army occupied the capital Phnom Penh, and Pol Pot and the Khmer Rouge retreated to the jungles near the Thai border.