Ibrahim became active as a rebel following the damaging
civil war of 811–813 between the rival caliphs
al-Amin and al-Ma'mun, which had greatly weakened the ability of the Abbasid government to maintain its authority in
Baghdad and the provinces of the empire. While in
Mecca in 815, he was appointed by
Abu al-Saraya al-Sari ibn Mansur, who had launched a pro-Alid revolt in southern
Iraq and seized the cities of
al-Kufah,
al-Basrah, Mecca, and
Medina, to conquer the
Yemen on his behalf, and he accordingly marched south toward the province with a large force. Upon learning of his advance, the governor of the Yemen,
Ishaq ibn Musa ibn Isa al-Hashimi, decided against putting up any resistance and instead withdrew with his troops for the
Hijaz, in effect surrendering the province to Ibrahim. The latter was consequently able to enter the Yemen without facing any significant resistance, and he proceeded to occupy
Sana'a in September 815 and take control of the country. Ibrahim was able to maintain his hold over the Yemen for approximately a year, during which time he minted coins in his own name. His severe administration of the province, which was characterized by frequent killings, acts of enslavement, and confiscations of private property, soon caused him to develop a reputation for brutality, and he became known by the title of al-Jazzar ("the Butcher"). Especially harsh measures were taken on behalf of his tribal allies, who assisted him in his rule of the country, and at their request he arrested several chiefs of their rivals, killing several of them and forcing others into exile. After spending several months in the Yemen, Ibrahim attempted to assert his authority over Mecca as well, and dispatched an army to the city to lead the
pilgrimage of 816 in the name of the Alids. Upon their arrival at Mecca, however, his forces were unable to enter the city due to the presence of Abbasid reinforcements, and instead took to conducting raiding activities in the neighboring area until they were defeated and dispersed. Soon afterwards, Ibrahim learned that another army under the command of
Hamdawayh ibn Ali ibn Isa ibn Mahan was marching toward the Yemen in order to reassert government control over the province, and he set out with his own men to halt Hamdawayh's advance. In the resulting engagement, Ibrahim was defeated and put to flight, and Hamdawayh was able to enter Sana'a and establish himself as governor, putting an end to Alid rule of the province. ==Seizure of Mecca==