Why Vietnam is an S
Vietnam is two river deltas joined by a thin coastal strip, squeezed between the sea and the mountains of the Annamese Cordillera. The shape comes from centuries of expansion south along that coast, from the Red River delta around Hanoi to the Mekong delta, which Vietnam reached only in the 1700s.
Written from cited sourcesLast checked 30 September 2026Suggest a correction
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Two deltas and a strip
Vietnam runs about 1,650 km from north to south but is only about 50 km wide at its narrowest.[1] Its main features are the Annamese Cordillera, which runs through central Vietnam from northwest to southeast, and two large deltas: the Red River’s in the north and the Mekong’s in the south, joined by a long, narrow coastal plain.[1]
In the centre the mountains run parallel to the coast, with peaks above 1,800 metres, and spurs reach right into the sea, cutting the coast into isolated sections. On the other side of the range lie Laos and Cambodia, and crossing it is difficult.[1]
Moving south
The Vietnamese state began in the Red River delta, which entered written history when China’s expansion reached it in the 3rd century BCE. Vietnam threw off Chinese rule in 938.[1]
From there it expanded south along the coastal plain, conquering the kingdom of Champa in 1471 and later taking parts of the Khmer empire, including the Mekong delta. By 1757 Vietnam had largely reached its present size, and Soc Trang was annexed in 1840.[1] The mountains, the deltas and the long coastal plain between them shaped where people settled, and made the country hard for invaders to conquer.[1]
Split into three, and into two
France took the south first, making it the colony of Cochinchina in the 1860s. In 1883 the Vietnamese court accepted French protectorates over the north, which the French called Tonkin, and the centre, which they called Annam. From 1887 all three were part of French Indochina with Cambodia and later Laos.[2]
The Geneva Accords of 1954 divided the country temporarily at 17°N, the “17th parallel”. The elections meant to reunite it in 1956 were never held.[3]
Timeline
938
Independence from China
Vietnam ends Chinese rule over the Red River delta.[1]
1471
Champa conquered
Vietnam pushes south along the coast.[1]
1757
Present size
Expansion into the Mekong delta is largely complete.[1]
1862
Cochinchina
Vietnam cedes the first southern provinces to France.[2]
1883
Tonkin and Annam
The north and centre become French protectorates.[2]
1954
17th parallel
The Geneva Accords divide the country into two zones.[3]
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Sources
- [1]Vietnam · Encyclopaedia Britannica
- [2]Vietnam: The conquest of Vietnam by France · Encyclopaedia Britannica
- [3]Vietnam: The two Vietnams (1954–65) · Encyclopaedia Britannica
Map geometry from Natural Earth via world-atlas. See credits.