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 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 …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 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 and as of 2023 it had a population of 807,300.