On 11 March 2011, the UNASUR treaty entered into force. UNASUR (the Union of South American Nations) is a regional organisation that comprises all twelve South American countries: Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Guyana, Paraguay, Peru, Suriname, Uruguay and Venezuela. The entry into force of the treaty is an important development for the international arbitration community given some of the proposals that UNASUR is advancing, particularly in the field of investor-State arbitration.