Vietnam was a country in Asia.
During the 1960s and 1970s, a war was fought in the country in which the United States participated. (PROSE: Wonderland, Salvation)
In the 1960s, the Fifth Doctor, Nyssa, Wilton, Mulberry and Floyd visited Vietnam and met Major Alice Hunniford. (AUDIO: Renaissance of the Daleks)
On 24 December 1969, the Third Doctor and Sarah Jane Smith visited Saigon, Vietnam during the Christmas ceasefire. (PROSE: Interesting Times)
In 1979, China invaded Vietnam. (TV: Tooth and Claw)
The Chinese three-striped box turtle was found in Vietnam. (PROSE: The Last Dodo)