People's Liberation Army troops entered Friendship Pass on 11 December 1949.Marshal Su Yuanchun and his entourage passing through the since-removed outer gatehouse on 16 July 1900.
Picture from Bắc Sứ Thủy Lục Địa Đồ 北使水陸地圗, depicting the "South Suppressing Pass" (Trấn Nam Quan; 鎮南關) in 1880 (Tự Đức Canh Thìn niên; 嗣徳庚辰年).
Traditionally, the pass served as the exact border between China and Vietnam,[1][2] hence there is also a Vietnamese historical saying: "Nước Việt Nam ta trải dài từ Ải Nam Quan đến mũi Cà Mau,"[3][unreliable source?][4][unreliable source?] translated as "The Vietnamese nation stretches from Ải Nam Quan to Cape Cà Mau". However, since the Franco-Qing Convention of 1887, the border has been determined to be south of the Pass itself, putting it entirely within Chinese territory,[5] in Pingxiang, Chongzuo County, Guangxi Autonomous Region,[6] and the official border between the two nations is beyond this pass. A border stone No. 18 was erected and represented on an 1894 map to be "along the road from Đồng Đăng to Nam Quan", but has since been lost.[7] When China and Vietnam negotiated for a new border, both recognized the 1887 border to be a legal reference point through an agreement signed in 1993,[8] and both chose to draw the border south of, although at different distances away from, the Pass, later agreeing on a compromise. The new border was confirmed by Chinese and Vietnamese officials by a border treaty enacted in June 2000,[1] causing controversy among some Vietnamese as well as members of Vietnamese diaspora, who deemed it a "concession" to China.[9]
