This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Vietnam's long S-curve down the eastern edge of mainland Southeast Asia is really a story about two deltas joined by a narrow spine. The Red River Delta in the north, where Hanoi sits, and the Mekong Delta in the south, where Ho Chi Minh City anchors a vastly larger and flatter plain, are the country's two demographic and agricultural centers, each built by a different river system draining a different set of mountains. Between them runs a long, narrow, mountainous waist where the country is, at its thinnest, barely thirty miles wide, coastline on one side and the Annamite mountain spine dividing Vietnam from Laos on the other. That geography shaped the country's history as much as any war did: a north and a south with genuinely different rivers, soils and growing seasons, connected by a coastal corridor too narrow and too mountainous to unite them easily, which is part of why division along the 17th parallel found such a natural line to follow when it came.