Not an expert on Vietnam martial arts:

While stationed at Algiers Naval Station (New Orleans, LA between 1978-82?) I met some Vietnamese who siad that there is a martial arts tradition but it was kind of lost until some Vietnamese who studied Chinese or Japanese traditions attempted to re-introduce that long lost treasure. There was always a strong Chinese presence in Vietnam and intermarriage tended to create a reconstruction of what was named NamViet Martial Arts, usually a product of the individuals who created this new reality.