Bhutan's regional groupings: SAARC, BIMSTEC and the Colombo Plan
Background
SAARC was established on 8 December 1985 with the adoption of its Charter in Dhaka by the Heads of State or Government of Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan and Sri Lanka.
Afghanistan joined SAARC in April 2007 as the eighth member; the SAARC Secretariat is in Kathmandu.
Bhutan hosted the 16th SAARC Summit in Thimphu in 2010.
BIMSTEC was created by the Bangkok Declaration of 1997; its current name was adopted in 2004 following Bhutan and Nepal's admission.
Bhutan joined the Colombo Plan in 1962.
In plain words
SAARC South Asian Association for Regional Cooperation — Regional body whose Charter was adopted in Dhaka in 1985.
BIMSTEC Bay of Bengal Initiative for Multi-Sectoral Technical and Economic Cooperation — Seven-member group of five South Asian and two South-east Asian states.