The northern region has several mountain ranges whose peaks exceeding 2,000 meters, in Xiangkhoang Plateau is of the highest mountains of Laos, Phou Bia (2,820 metres). Towards the east id the Annamite chain marks the border with Vietnam, the central region of the country is occupied by a series of limestone plateaus, as the Plateau of Khammouan, in the south lies the Boloven Plateau. Laos has a poor economy based on agriculture, the more important cultivation is rice, other products are cassava, potatoes, corn, tobacco, cotton, coffee. Important to the economy are the freshwater fisheries and livestock. Forests provide teak and other wood. Poor mineral resources limited to gypsum, coal and tin.