- a maritime region in W South America: long in dispute between Chile and Peru; annexed by Chile 1883; divided as a result of arbitration 1929 into a Peruvian department (Tacna ) and a Chilean department (Arica ).
- a coastal desert region of W South America, long disputed by Chile and Peru: divided in 1929 into the Peruvian department of Tacna and the Chilean department of Arica
