Bolivia is a landlocked country that borders five South American countries: Chile to the west, Brazil to the east, Peru to the north and Argentina and Paraguay to the south. Bolivia's lack of sea access poses a major geographical challenge, as the country struggles to integrate itself into the global economy. As a result, Bolivia's major trade partners are its neighbors, Brazil and Argentina. Bolivia's history is full of major territorial defeats. The country lost its sea access to Chile after the War of the Pacific, which was fought from 1879 to 1884. Bolivia has also suffered territorial losses to Argentina, Brazil, Chile, Paraguay and Peru. While the country has settled its border disputes with most of these countries, it still claims the territory it lost to Chile. Every Bolivian administration has prioritized attempts to gain access to the Pacific Ocean. Bolivia is extremely divided geographically and ethnically; the Andes mountains divide the country's lowlands and highlands, making it one of the most politically unstable countries in South America. The highlands are predominantly made up of indigenous groups, mostly the Aymara and Quechua peoples, while lowlands residents are mostly Mestizo. The core of Bolivia's highlands is the La Paz metropolitan area, where the city of El Alto is also located. The core of Bolivia's lowlands is Santa Cruz, which is the country's richest department. The disconnect between the highlands and lowlands has resulted in strong regionalism in the country. Political groups from the more developed departments located in the lowlands, where most of Bolivia's agricultural and natural gas production take place, have historically demanded more autonomy from the central political authority located in La Paz.