Nga Sơn is a district of Thanh Hóa province in the North Central Coast region of Vietnam. The district capital is Nga Sơn. The district features many historical vestiges. These include Từ Thức grotto, Tien Pagoda, and legends referring to Mai An Tiêm who, the story goes, was exiled to the then uninhabited islands, now known as Nga Son and Thanh Hoa. Nga Sơn villagers were known for planting sedge-a grass-like plant with triangular stems, and weaving mats.