Đồng Đăng Railway Station and the town are several kilometres short of the Friendship Pass border crossing. It is one of three main border crossings with China, the others being Móng Cái-Dongxing, Guangxi to the East on the coast, and Lào Cai-Hekou, Yunnan, inland 150 km northwest. A fourth crossing is the Trà Lĩnh District-Longbang, Guangxi crossing.
The town was the site of the Battle of Đồng Đăng in 1885.
In September 1940 a group of Japanese officers, in spite of an agreement signed the 22nd, attacked Đồng Đăng and laid siege to Lam Sơn, beginning the Japanese invasion of French Indochina. In March 1945 the Japanese again attacked, and it was the site of the fiercest fighting of the March coup d'état, when a company of Tonkinese Rifles and a battery of colonial artillery held off the invaders for three days before being massacred by them.
- Vietnam 10 - Page 158 Nick Ray, Yu-Mei Balasingamchow, Iain Stewart - 2009 "border crossing: youyi guan–Huu nghi quan - The Friendship Pass at Dong Dang–Pingxiang is the most popular border crossing in the far north. The border post itself is at Huu Nghi Quan (Friendship Gate), 3km north of Dong Dang town; a xe om"
- China's Southwest 3rd Edition - Page 485 Damian Harper - 2007 "As train tickets to China are expensive in Hanoi, some travellers buy a ticket to Dong Dang, walk across the border and then buy a train ticket on the Chinese side. This isn't the best way, because it's several kilometres from Dong Dang to Friendship Pass, and you'll have to hire someone to take you by motorbike. If you're going by train, it's best to buy a ticket from Hanoi to Pingxiang,"
- Rough Guide to China - Page 20 David Leffman, Simon Lewis, Jeremy Atiyah - 2003 "Vietnam has three border crossings with China - Dong Dang, 60km northeast of Hanoi; Lao Cai, 150km northwest; and the little-used Mong Cai, 200km south of Nanning. All three are open daily between 8.30am and 5pm. Vietnamese border .."