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.

Lạng Sơn is a province in northern Vietnam. Its capital is also called Lạng Sơn, which is a strategically important town at the border with China and is 137 kilometres (85 mi) northeast of Hanoi connected by rail and road. Lạng Sơn province is bordered by Cao Bằng province, Bắc Giang province, Bắc Kạn province, Quảng Ninh province, Thái Nguyên province, and China's Guangxi province. The province covers an area of 8,310.18 km2 (3,208.58 sq mi) and as of 2008 it had a population of 781,655.