The contractor worked near Basra, and this work involved great mounds. A Persian man named Ali appeared, who succeeded in explaining the injustice suffered by these workers. He showed them that their misfortune stemmed from the Abbasid governors, and promised them that if they revolted, injustice would be removed, justice would be achieved, and he promised to improve their condition, guarantee their freedom, and raise their standard of living. They revolted and took control of Basra and its surroundings, and built a new town of mud bricks and named it Al-Mukhtarah. He may have chosen this name in allusion to Al-Mukhtar al-Thaqafi, who invented the new Mahdi idea. The Bedouins who were neighbors to the Zanj joined them. They plundered Basra and attacked the Muslims during Friday prayer, killing about three hundred thousand people in the mosque and from the people of Basra. The Abbasid Caliph appointed his brother Al-Muwaffaq to quell this revolt, which lasted for years and put the country in danger.