This one looks tricky. Looks like on a larger level there are only three administrative regions, but then there are 58 provinces + 5 municipalities.
Could divide it by the eight sub-regions
Northern Vietnam includes the following subregions:
- Northwest (Tây Bắc)
- Northeast (Đông Bắc)
- Red River Delta (Đồng Bằng Sông Hồng)
Central Vietnam includes the following subregions:
- North Central Coast (Bắc Trung Bộ)
- South Central Coast (Nam Trung Bộ)
Southern Vietnam includes the following subregions:
- Central Highlands (Tây Nguyên - meaning western whole)
- Southeast (Đông Nam Bộ)
- Mekong River Delta (Đồng Bằng Sông Cửu Long)
Seems like a good option
Ok so this list is the going one?
Northwest
Northeast
Red River Delta
North Central Coast
South Central Coast
Central Highlands
Southeast
Mekong River Delta