Etymology

The first Spanish conquistadors discovered the Río de la Plata, and they named the estuary Mar Dulce ('Sweet Sea', as in a fresh water sea). Indigenous people gave gifts of silver to the survivors of the shipwrecked expedition, who were led by Juan Díaz de Solís. The legend of Sierra del Plata – a mountain rich in silver – reached Spain around 1524, and the name was first seen in print on a Venice map from 1536. The source of the silver was the area where the city of Potosí was to be founded in 1546. An expedition that followed the trail of the silver up the Paraná and Pilcomayo rivers finally reached the source only to find it already owned by explorers who reached it from Lima, the capital of the Viceroyalty of Peru.
The name Argentina (from Latin argentum: silver) was first used extensively in the 1612 book Historia del descubrimiento, población, y conquista del Río de la Plata (History of the discovery, population, and conquest of the Río de la Plata) by Ruy Díaz de Guzmán, naming the territory Tierra Argentina (Land of Silver). Traditionally, the British English name for the country is "The Argentine", but this is no longer in common use.