The Southeastern Anatolia Region Municipalities Union's establishment process began after a meeting held at the GAP Development Administration in Şanlıurfa on September 4, 1990, upon the invitation of the Prime Ministry's GAP Regional Development Administration. During this meeting, attended by the mayors of the GAP Region (Diyarbakır, Gaziantep, Siirt, Şırnak, Batman, Şanlıurfa, Mardin, Adıyaman), the GAP Administration President, and the GAP Development Administration Regional Director, a consensus was reached on establishing the GAP Region Municipalities Union.
Subsequently, an application was made to the Diyarbakır Governorship by the mayor of Diyarbakır on December 25, 1990. The Governorship forwarded the application to the Ministry of Interior on December 27, 1990.The Ministry of Interior presented this request to the Council of Ministers, and with the Council of Ministers' decision dated January 25, 1991, and numbered 91/1427, the union's establishment was approved, and it began its services. The union's name was later changed to the SOUTHEASTERN ANATOLIA REGION MUNICIPALITIES UNION (GABB).
