Bolivia /bəˈlɪviə/ (listen), officially the Plurinational State of Bolivia, is a landlocked country located in western-central South America. The constitutional capital is Sucre, while the seat of government and executive capital is La Paz. The largest city and principal industrial center is Santa Cruz de la Sierra, located on the Llanos Orientales (tropical lowlands), a mostly flat region in the east of the country. The sovereign state of Bolivia is a constitutionally unitary state, divided into nine departments. Its geography varies from the peaks of the Andes in the West, to the Eastern Lowlands, situated within the Amazon basin. It is bordered to the north and east by Brazil, to the southeast by Paraguay, to the south by Argentina, to the southwest by Chile, and to the northwest by Peru. One-third of the country is within the Andean mountain range. With 1,098,581 km (424,164 sq mi) of area, Bolivia is the fifth largest country in South America, after Brazil, Argentina, Peru, and Colombia (and alongside Paraguay, one of the only two landlocked countries in the Americas), the 27th largest in the world, the largest landlocked country in the Southern Hemisphere, and the world's seventh largest landlocked country, after Kazakhstan, Mongolia, Chad, Niger, Mali, and Ethiopia. The country's population, estimated at 11 million, is multiethnic, including Amerindians, Mestizos, Europeans, Asians, and Africans. Spanish is the official and predominant language, although 36 indigenous languages also have official status, of which the most commonly spoken are Guarani, Aymara, and Quechua languages. Before Spanish colonization, the Andean region of Bolivia was part of the Inca Empire, while the northern and eastern lowlands were inhabited by independent tribes. Spanish conquistadors arriving from Cusco and Asunción took control of the region in the 16th century. During the Spanish colonial period Bolivia was administered by the Real Audiencia of Charcas. Spain built its empire in large part upon the silver that was extracted from Bolivia's mines.