When he had gathered a considerable following Abu Saʿid established himself at the town of al-ʾAhsa, besieged Hajar, the capital of the Bahrayn, for a matter of two years, during which his followers were considerably increased, and finally captured the town by cutting off its water supply. Some of the inhabitants escaped to the islands in the river near by, others embraced Abu Saʿid’s doctrines, whilst others were put to death. The town was pillaged and ruined, and thus al-ʾAhsa afterwards replaced it as the capital of the Bahrayn. According to Ibn Khallikan Abu Saʿid first appeared as _kabir_ or “great man” of the Qarmatians in 286. In 287 they made an attempt on Basra, and though they defeated the forces sent by the Khalif to repel them, they were unable to take the city (Ibn Khall., i. 427). Abu Saʿid then attempted to get possession of Oman, but was obliged to abandon this scheme. He was slain in 301 with several other Qarmatian leaders, and was succeeded by his son Abu l-Kasam Saʿid, who held the leadership until his second son Abu Tahar, who had been designated successor, was old enough to take up the task, which happened in 305. The Qarmatian risings which take a position of considerable prominence in later history all took place under the successors of Abu Saʿid, who may be regarded as the founder of the Qarmatians as a revolutionary force, although there had been an earlier beginning of the sect as an off-shoot of the Ismaʿilians under Hamdan and his missionaries. According to Ibn Khallikan Abu Saʿid entered Syria in 289, and in 291 he was slain in his bath by one of his eunuchs. He left six sons. It was Abu Tahar who marched on Basra in 311, occupied it without serious resistance, and plundered the city. But to these doings of the Qarmatians we shall return later. IV ESTABLISHMENT OF THE FATIMIDS IN NORTH AFRICA