Thất Nguyên

Thất Nguyên was an old district of the mountainous country north of Lạng Sơn. Its valleys lie near routes leading towards the frontier with Guangxi, amid the hills of Tràng Định. The name appears in historical accounts under the Lý and Ming periods, while the Mạc dynasty later used the form Thất Tuyên. Rivers and streams wind through the narrow valleys between forested ridges.