ASEAN Association of Southeast Asian Nations (ASEAN: The Association of South East Asian Nations) was established on 8 August 2510 by founding ASEAN is Thailand, Indonesia, Malaysia, Philippines and Singapore later in the year.. 2527 Brunei Darussalam has joined. Followed by Vietnam Member since 2538, while Laos and Myanmar became a member in 2540 and the last one is Cambodian. He is a member of ASEAN in 2542, when the current ASEAN member countries, all 10 countries.