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.

Quảng Ninh or Quangninh is a province along the northeastern coast of Vietnam. It is about 153 km (95 mi) east of Hanoi, comprising four cities, two district-level towns and seven rural districts. The provincial capital is Hạ Long. The province covers an area of 6,207.95 km2 (2,396.90 sq mi) and, as of 2023, had a population of 1,413,452. Nearly 80% of the province is mountainous with abundant land, forest, water and mineral resources, with 90% of Vietnam's coal output extracted from the province. The province is also home to Hạ Long Bay, a World Heritage Site that has 1,969 islands, out of which 989 have been given names.