Upvote:1
This is a tricky question to answer. According to Keith Weller Taylor's well researched "The Birth of the Vietnam" the Vietnamese as the ethnic group they are now came into being after independence from China. Nevertheless during Chinese rule there was most probably a noticeable distinction between people from China and the local ethnic groups. However according to Taylor there was a marked distinction as well between the heavily sinicized inhabitants of the Red river delta and the people from the mountains to the south in HΓ TΔ©nh and Nghα» An, who came to dominate the Red river delta militarily after the Chinese left. According to Taylor the Vietnamese as an ethnic group came into being as an admixture between the sinicized inhabitants of the Red river delta and the rustic warriors from the mountains, while the contrast to China furthered a sense of ethnic self awareness.
Upvote:4
Barring positive evidence of large-scale population movement since 983 AD, this ethnographic map of Vietnam in 1970 (from here) would seem to be definitive that the Vietnamese people achieved their own independence. It seems well established that the people of the Red River Delta led the fight for independence - an area today predominantly ethnic Vietnamese.