 During this period his representative, the "Dāʿī", maintained the community.The names of the eighth, ninth, and tenth Imams are considered by some traditions to be "hidden", known only by their nicknames due to threats from the Abbasids.The 11th Imam, Abdullah al-Mahdi Billah, founded the Fatimid Caliphate in 909 CE in "Ifriqiya" (which includes present Tunisia in North Africa), ending the first occultation.