Karmathians or Carmathians (kärmā´thēənz), a Muslim sect of the 9th and 10th cent., similar to the Assassin sect. They were part of a movement for social reform that spread widely through Islam from the 9th to the 12th cent. They were organized according to initiation and illumination, like other similar sects of the period. Although heretical, their doctrine had a great influence on Islamic philosophy and remnants of it are today found in the religion of the Druze. The chief importance of the Karmathians came with their establishment of an independent communist community in lower Mesopotamia before 900. They were the source of rebellions in Khorasan and Syria, and after 900 they conquered all of Yemen. In spite of the efforts of the Abbasid caliph at Baghdad, the Karmathians continued their career until (c.930) they created a sensation that rocked Islam by carrying away the Black Stone from the Kaaba at Mecca. Ten years later the Karmathians returned the stone. They were in constant touch with the founders of Fatimid rule in Egypt, alternately at war or peace with them. They ceased to be a political power after 1000.