2 The Ottoman Conquest of Yemen: The Ismaili Perspective Samer Traboulsi 41 T ayyibi Ismaili cosmological doctrine divides the universe into two worlds: the world of creation ( ʿ ālam al-ibdā ʿ ), con- sisting of a neoplatonic hierarchy of ten intellects and the ten spheres of the universe, and our world of religion ( ʿ ālam al-dīn), which is organized into recurring cycles and megacycles of proph- ets, speakers (nāṭiq, plural nuṭaqā ʾ ), and imams to mirror those in the world of creation. 1 The worldly cycles alternate between peri- ods of manifestation (kashf ) and periods of concealment (satr). Currently, we live in a period of concealment that began with the occultation of Imam al-Tayyib around 524/1129 in Fatimid Cairo. Under the leadership of the Sulayhid queen Arwa bint Ahmad (d. 532/1137), the Ismaili communities in Yemen and India opted to follow al-Tayyib and his descendants in concealment, hence their designation as Tayyibi Ismailis. 2 During the absence of the imam, the community is led by a chief dā ʿ ī (missionary), the dā ʿ ī muṭlaq, and a number of religious clerics, the ḥudūd, who are distributed among the community. The period from the time the chief dā ʿ ī took charge of the da ʿ wa (proselytizing mission) in Yemen until the day the Tayyibis decided to move to Gujarat, India, in 974/1567 saw some glory days and numerous setbacks; these led one of the dā ʿ ī s to describe this period of concealment as “the greatest and