Rugby was originally introduced when Vietnam was part of French Indochina, but this was mainly by French expatriates. After independence there was a long hiatus, as financial and political forces, from famine to the Vietnam War meant it was impossible for the game to be played.
The historical connection with France is a mixed blessing. A number of people who could qualify for Vietnam's national team play in France. An example is the MHRC played François Trinh-Duc, who has a Vietnamese grandfather.