Lạng Sơn is a province in far northern Vietnam, bordering Guangxi province in China. 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 bounded by China in the north, Cao Bằng Province borders the northwest, Ha Bac Province on the south, Quảng Ninh Province starting on the south and extending to the eastern border and Thái Nguyên Province to the west.The province covers an area of 8327.6 square kilometres and as of 2008 it had a population of 759,000 people.