Cổ Đằng

Cổ Đằng lies on the coastal plain north of the Mã River in Thanh Hóa. The low-lying country was formed by the river's deposits, and its villages spread between waterways and the sea. The district took the name Cổ Đằng during the reign of the Trần king Anh Tông. Its old lands are associated with Hoằng Hóa, where the Mã divides into branches as it approaches the coast.