An Isma'ili Shia militant movement and breakaway religious state centered on the al-Ahsa oasis in Eastern Arabia, led by the dynasty founded by Abu Sa'id al-Jannabi, which rejected both Abbasid and Fatimid claims to the imamate.
The dynasty's descendants ruled at al-Ahsa until 1077; the movement is also remembered for sacking Mecca and seizing the Black Stone in 930.
No dedicated Open-Library-verifiable monograph solely on the Qarmatians was found; Daftary's authoritative Ismaili history has substantial, specific treatment of the Qarmatian movement and state, and is directly quoted in the Wikipedia article itself.