Traditionally, the pass served as the exact border between China and Vietnam, 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, in
Pingxiang,
Chongzuo County,
Guangxi Autonomous Region, 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. 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, 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, == References ==