The first stamp issuer in the alphabet is the sheikdom of Abu Dhabi on the Persian Gulf. It had become a British protectorate in 1890 but only issued its own stamps between 1964 and 1972. The treaty of protection ended when the emirate joined the other Trucial States to form the United Arab Emirates on December 1, 1971.
The stamp pictured is #1 in the Scott Standard Postage Stamp Catalogue and is part of a set of general issue postage stamps released on March 30, 1964. The bright yellow green stamp is denominated 5 naye paise (100 of which equaled one rupee at the time). The stamp portrays Sheik Shakbut bin Sultan.