Haile Selassie's rule ended on 12 September 1974, when he was deposed by the Derg, a Soviet-backed Marxist–Leninist leadership led by Mengistu Haile Mariam. The new Provisional Military Administrative Council established a one-party communist state in March 1975. The regime promised autonomy and national self-determination to Ethiopia's numerous ethnic groups in reverse from Haile Selassie's policy of unitary and ethnolinguistically homogenous statehood, as centered around the Amharas and the Amharic language. To this end, in 1987, the Derg promulgated a Constitution modelled on the Soviet Constitution with such provisions.