The China–Vietnam border is the international boundary between China and Vietnam, consisting of a 1,297 km (806 mi) terrestrial border stretching from the tripoint with Laos in the west to the Gulf of Tonkin coast in the east, and a maritime border in the Gulf of Tonkin and South China Sea.

Móng Cái is a city of Quảng Ninh Province in northern Vietnam. Located on China–Vietnam border, it sits on the southern bank of Beilun River across Dongxing city of China's Guangxi Autonomous Region. It has a population of about 108,553 in 2019. One of these areas is the Trần Phú ward.