The concept of Regional Organizations mainly originated after the end of second world war. Regional organizations are a parts of Supranational/Global Governance.
ASEAN
Association of South East Asian Nations
Member States: 10 (Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, Philippines, Singapore, Thailand, Vietnam)
Founded: August 8, 1967, Thailand
Headquarter: Jakarta, Indonesia
BIMSTEC
Bay of Bengal Initiative for Multi Sectoral Technical and Economic Cooperation
Member States: 7 (Bangladesh, Bhutan, India, Myanmar, Nepal, Sri Lanka, and Thailand)
Founded: June 6, 1997, Bangkok Thailand
Headquarter: Dhaka, Bangladesh
SCO
Shanghai Cooperation Organization
Member States: 8 (China, Kyrgyzstan, Russia, Tajikistan, Uzbekistan, India, Pakistan, Kazakhstan)
4 observer states: Afghanistan, Belarus, Iran, Mongolia
6 dialogue partners: Armenia, Azerbaijan, Cambodia, Nepal, Sri Lanka, Turkey
4 guest attendances: Association of Southeast Asian Nations, Commonwealth of Independent States, Turkmenistan, United Nations
Founded:19 September 2003 (Shanghai Five group, founded on 26 April 1996), Shanghai China
Headquarter: Shanghai China
SAARC
South Asia Association for Regional Cooperation
Member States: 8 (Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, Sri Lanka)
Founded: December 8, 1985, Dhaka, Bangladesh
Headquarter: Kathmandu, Nepal
OPEC
Organization of the Petroleum Exporting Countries
Member States: 12 (Indonesia, Saudi Arabia, Iran, Venezuela, Libya, Nigeria, Iraq, United Arab Emirates, Algeria, Kuwait, Angola, Gabon)
Founded: September 1960, Baghdad, Iraq
Headquarter: Vienna, Austria (Other than member state*)
EU
Member States: 27 (Austria, Belgium, Bulgaria, Croatia, Cyprus, Czechia, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden)
Founded: November 1, 1993, Maastricht, Netherlands
Founders: Germany, France, Italy, Netherlands, Belgium, Luxembourg
Headquarter: Brussels, Belgium
Colombo Plan
Colombo Plan for Cooperative Economic and Social Development in Asia and the Pacific
Member States: Regional organization of 27 countries
Founded: By Great Britain in Colombo, Ceylon, in 28 November 1950
Headquarter: Colombo, Sri Lanka