The Mường Thanh Valley is a valley located in the Điện Biên Province of Northwestern Vietnam. The valley is approximately 20 km long by 5 km wide. A heart-shaped basin, the valley is surrounded by a region filled with jungles, rice paddies, and lakes. Located within the Mường Thanh Valley is the city of Điện Biên Phủ. The capital of Điện Biên Province, Điện Biên Phủ, is famous as the site of a decisive battle in 1954 in which French forces were defeated by Việt Minh troops.