Qarmatian, member of an Ismāʿīlī Shiʿi movement that rejected the claim of the Fāṭimid caliph ʿUbayd Allāh to the imamate. The Qarmatians flourished in Iraq, Yemen, and especially Bahrain during the 9th to 11th centuries, taking their name from Ḥamdān Qarmaṭ, who led the sect in southern Iraq in the second half of the 9th century. The Qarmatians became notorious for an insurrection in Syria and Iraq in 903–906 and for the exploits of two Bahraini leaders, Abū Saʿīd al-Jannābī and his son and successor, Abū Ṭāhir Sulaymān, who invaded Iraq several times and in 930 sacked Mecca and carried off the Black Stone of the Kaaba.