During the first years of the 20th century, the border between the two nations in Patagonia was established by the mediation of the British crown. Numerous modifications have been made since then, the last conflict having been resolved in 1994 by an arbitration tribunal constituted in Rio de Janeiro. It granted Argentina sovereignty over the Southern Patagonia Icefield, Cerro Fitz Roy, and Laguna del Desierto.[53][54][circular reference]