The 20th Fatemi imam, Al-Aamir be Ahkaam AllahAS recognized that the time had come for the imam to keep away from the public eye and made elaborate preparations for his successor, his son Al-TayyibAS, to go into seclusion at the appropriate moment and also for the preservation and continuation of the Fatimi tradition in Yemen.
Imam al-TayyibAS went into seclusion in 1132 AD and thus from Egypt the centre of Fatimi authority and activity was shifted to Yemen.
For this purpose Imam Al-AamirAS directed his grand emissary in Yemen, the Sulayhid queen al-Hurrah al=MalikahRA, to establish the office of al da`i al mutlaq, a vicegerent of the imam who was to function during the time of seclusion in his place, invested with his absolute authority. Each dai mutlaq is duty-bound to appoint a successor in his own lifetime who will always carry on the mission – the 'd`awat' - in the name of the imams with all the authority and power inherent in that high office.
The chain of da`is (pl. du`aat) has continued without interruption to this day. The first to enter upon the august office in Yemen was Syedna ZoebRA. In all 23 du`aat functioned in Yemen before the seat of authority shifted to India.