Laos–Vietnam border

A line inside French Indochina

For centuries the Annamite Range was a buffer zone between the Khmer empire and the Annamese and Champa kingdoms, and later between Laos and Annam. France took Cochin China from 1862, Annam and Tonkin in 1884 and Laos in 1893, and the Laos–Vietnam line was drawn by administrative decisions within French Indochina.^[1]

For almost 1,150 miles it follows the main water divide of the mountains, with another 148 miles along rivers and two straight stretches. One dispute arose, west of Vietnam’s demilitarised zone, where North Vietnamese forces occupied Lao land in 1954 and 1958; Laos cited a treaty going back to 1364 and a French decree of 2 October 1916 that set the line there.^[1]

Independence and war

Vietnam became independent on 8 March 1949 and Laos on 19 July 1949, and after the 1954 Geneva conference most of the border faced communist-ruled North Vietnam. In 1966 the US Geographer noted that North Vietnam’s support for the Pathet Lao and its intervention in South Vietnam involved crossing this frontier, along routes such as National Routes 7, 8 and 9.^[1]

Marked out again

On 18 July 1977 Vietnam and Laos signed a convention demarcating their border, and between 1978 and 1987 they marked it on the ground, including transfers of land, people and property. Supplementary documents followed in 1986 and 1987.^[2]

From 2008 to 2016 a joint project added and upgraded markers, bringing the total to 1,002 markers and posts at 905 positions. A protocol signed on 16 March 2016 records the line, and it took effect on 5 September 2017 with an agreement on managing the border and its crossings.^[2]