Quan Da Châu

Quan Da was a mountainous district of western Thanh Hóa, extending into the upper Mã River country towards Laos. Forested ridges divide its valleys, and the Luồng and Lò rivers flow east to join the Mã. The name was used in the Lê period; in 1835, under Emperor Minh Mạng, Quan Da was combined with neighbouring Tàm to form the district of Quan Hóa.