Brazil is the South American country that shares land borders with ten other countries.
Those neighbours are Argentina, Bolivia, Colombia, Guyana, Paraguay, Peru, Suriname, Uruguay, Venezuela and France, because French Guiana is an overseas department of France. Brazil therefore borders every independent South American country except Chile and Ecuador.
This enormous border network reflects Brazil’s position across much of the continent. Its frontiers extend from the Guiana region in the north to Uruguay in the south and include major rivers such as the Amazon, Paraná and Uruguay systems. Brazil’s total land boundaries stretch for roughly 16,885 kilometres.
A frequent counting mistake is to say Brazil borders nine countries and omit France. Another is to count territories rather than sovereign states: French Guiana is the territory, but France is the country. The Brazil–France frontier, along the Oyapock River, is the longest international land border involving France.