in control of the Bahrayni state, they launched raids along the pilgrim routes crossing the Arabian Peninsula: in 906 they ambushed the pilgrim caravan returning from Mecca and massacred 20,000 pilgrims. Under al-Jannabi (ruled 923–944), the Qarmaṭians came close to capturing Baghdad in 927, and sacked Mecca and Medina in 930. In their attack on Islam's holiest sites, the Qarmatians desecrated the Zamzam Well with corpses of Hajj pilgrims and took the Black Stone from Mecca to Ain Al Kuayba in Qatif. Holding the Black Stone to ransom, they forced the Abbasids to pay a huge sum for its return in 952. The revolution and desecration shocked the Muslim world and humiliated the Abbasids. But little could be done; for much of the tenth century the Qarmatians were the most powerful force in the Persian Gulf and Middle East, controlling the coast of Oman and collecting tribute from the caliph in Baghdad as well as from a rival Isma'ili imam in Cairo, the head of the Fatimid Caliphate, whose power they did not recognize. Qarmatian society The land they ruled over was extremely wealthy with a huge slave-based economy according to academic Yitzhak Nakash: Collapse According to Farhad Daftary, the catalyst of the collapse of Qarmatian movement as a whole happened in the year 931 CE when Abu Tahir al-Janabi – the Qarmatian leader in Bahrain – handed over the reins of the state in Bahrain to Abu'l-Fadl al-Isfahani, a young Persian man who had been believed by the Qarmatians to be the Mahdi. However, Abu Tahir soon realized al-Isfahani's appointment was a disastrous mistake, after the "Mahdi" executed some nobles and insulted Muhammad and the other prophets. The incident shocked the Qarmatians and the Islamic community as a whole, and Abu Tahir ordered the youth's execution. Leadership under al-Isfahani lasted only 80 days before his execution, but it greatly weakened the credibility of Qarmatians within the Muslim community in general, and heralded the beginning of the end of their revolutionary movements. After defeat by the Abbasids in 976, the Qarmatians began to look inwards and their status was reduced to that of a local power. This had severe consequences for the Qarmatians' ability to extract tribute from the region; according to Arabist historian Curtis Larsen: In Bahrain and eastern Arabia the Qarmatian state was replaced by the Uyunid dynasty, while it is believed that by the middle of the