How Vietnam Got its Name · Global Voices
Mong Palatino

Le Minh Khai traces the history of how Vietnam got its name and explains the inaccuracies in some historical accounts about the origins of the name.
Ultimately, the name Việt Nam is related to the Nguyễn clan’s southward expansion of the Lê Dynasty realm. What it signifies is that the Nguyễn created and ruled over something bigger than An Nam. It is a recognition of imperial expansion.