Before the War of the Pacific (1879–1883), the region belonged to Bolivia. In 1898, it was ceded to Argentina in exchange for recognition of Tarija as part of Bolivia. Chile, which had annexed the Litoral Province from Bolivia, declared the exchange illegal. The border was defined in 1899 after the Puna de Atacama dispute. Of the 75,000 km2 in dispute, 64,000 (85%) were awarded to Argentina and 11,000 (15%) to Chile.