Cambodian refugee at the Khao-I-Dang Refugee Camp, in Thailand, 1980. In 1979, Vietnam invaded Cambodia and overthrew the Khmer Rouge. Vietnam and the Cambodian government it created ruled the country for the next 12 years. The Khmer Rouge and other groups fought a guerrilla war against the Vietnamese occupiers and the Cambodian government. In 1979 and 1980, the chaos caused hundreds of thousands of Cambodians to rush to the Thailand border to escape the violence and famine that threatened Cambodia. Humanitarian organizations coped with the crisis in one of the largest humanitarian aid efforts ever undertaken.