The Puna de Atacama or Atacama Plateau is an arid high plateau averaging about 4500 metres (14,763.8 ft) above sea level and spanning an area of 180000 square kilometres (69,498.4 sq mi), in the Andes

Andes

The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...

 of northern Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

 and Argentina

Argentina

Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

 and southwest Bolivia

Bolivia

Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...

. Before the War of the Pacific

War of the Pacific

The War of the Pacific took place in western South America from 1879 through 1883. Chile fought against Bolivia and Peru. Despite cooperation among the three nations in the war against Spain, disputes soon arose over the mineral-rich Peruvian provinces of Tarapaca, Tacna, and Arica, and the...

 (1879-1883), the region belonged to Bolivia

Bolivia

Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...

. In 1898 it was ceded to Argentina in exchange for recognition of Tarija

Tarija, Bolivia

Tarija or San Bernardo de la Frontera de Tarixa is a city in southern Bolivia. Founded in 1574, Tarija is both the capital and largest city within the Tarija Department, with an airport offering regular service to primary Bolivian cities, as well as a regional bus terminal with domestic and...

 as part of Bolivia. Chile, which had annexed the Litoral Province

Litoral Province (Bolivia)

Litoral is a province in the southwestern parts of the Bolivian department of Oruro.-Location:Litoral Province is one of sixteen provinces in the Oruro Department...

 from Bolivia, declared the exchange illegal. The border was defined in 1899 after the Puna de Atacama Lawsuit.