Most areas of Viet Nam as the high mountains (particularly in the North) separated the Red River Plains and the Southern Plains of the Mekong River, as it also has a long narrow coastal stretch South from the North.
In Vietnam, most of the high mountains. (Especially northern), sandwiched between the Red River basin. And south of the Mekong River basin also has a narrow coastline. The length from north to south
The area of Vietnam are mostly high mountains (especially in the North) between the Red River Valley And the southern coastal plains river is also narrow, long from north to south.