ASEAN (ASEAN) or the Association of Southeast Asian Nations (Association of Southeast Asian Nations, the acronym ASEAN) was established on 8 August 2510 after the signing of a founding member of the ASEAN Declaration (The Bangkok. Declaration) Declaration or the full name is the Association of Southeast Asian nations (Declaration of ASEAN Concord) Forum at the Palace, Madeira. A founding member of the five countries, including Thailand, Singapore, Indonesia and the Philippines.