Hi Sandz
Sai Gon's fall ( Pearl of the orient etc ) was in 1975
liberated we may say by the Viet Cong
The lucky liberated southerners were then herded into re-education camps learning such things as the Communist party of Liberation was there to stay, elections werent that necessary and common ownsership by the people was a Good Thing. The only people who escaped this were the secret collaborators of whom the American found, there were Quite a Few
It took a few years for the future Boat People to realise that it wasnt gonna change in the near future. so they took to the boats in 1978-9
https://en.wikipedia.org/wiki/Vietnamese_boat_people
and I think they have done quite well as it was basically the economically educated trading classes that upped sticks and fled...
as with the ugandan asians ( 1973) the follow up data shows they didnt become a burden on the state ...