Lạng Sơn is a province in the Northeastern region of Vietnam. From four chronicles An Nam chí lược, An Nam chí nguyên, An Nam lai uy đồ sách and Đại Việt sử ký toàn thư, its name Lạng Sơn was originated from Tlủng-san in ancient Annamese language, which means "valleys + mountains (sơn)" in modern-Vietnamese.