Peru (; Spanish: Perú), officially the Republic of Peru (Spanish: República del Perú), is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the west by the Pacific Ocean. Peru is an extremely biodiverse country with habitats ranging from the arid plains of the Pacific coastal region in the west to the peaks of the Andes mountains vertically extending from the north to the southeast of the country to the tropical Amazon Basin rainforest in the east with the Amazon river. Peruvian territory was home to ancient cultures spanning from the Norte Chico civilization in Caral (one of the oldest in the world with settlements as old as 3200 BC) to the Inca Empire, the largest state in Pre-Columbian America. The Spanish Empire conquered the region in the 16th century and established a Viceroyalty with its capital in Lima, which included most of its South American colonies. Ideas of political autonomy later spread throughout Spanish America and Peru gained its independence, which was formally proclaimed in 1821 after the occupation by military campaigns of José de San Martín and Simón Bolívar and only after the battle of Ayacucho, three years after proclamation, Peru ensured its independence. After achieving independence, the country remained in recession and kept a low military profile until an economic rise based on the extraction of raw and maritime materials struck the country, which ended shortly before the war of the Pacific. Subsequently, the country has undergone changes in government from oligarchic to democratic systems. Peru has gone through periods of political unrest and internal conflict as well as periods of stability and economic upswing. Peru is a representative democratic republic divided into 25 regions. It is a developing country with a high Human Development Index score and a poverty level around 25.8 percent. Its main economic activities include mining, manufacturing, agriculture and fishing. The Peruvian population, estimated at 31.2 million in 2015, is multiethnic, including Amerindians, Europeans, Africans and Asians. The main spoken language is Spanish, although a significant number of Peruvians speak Quechua or other native languages. This mixture of cultural traditions has resulted in a wide diversity of expressions in fields such as art, cuisine, literature, and music.