Why did Yemen play an important role in the early Ismaili movement?

Yemen played a pivotal role in the early Ismaili movement primarily as a strategic base for the propagation of Ismaili doctrine. Around 880, Ismaili propaganda began to spread in Yemen, which served as a crucial launching point for the movement to reach North Africa.1

This expansion from Yemen was instrumental in the rise of the Fatimid dynasty, which eventually conquered Egypt and posed a significant challenge to the Abbasid Caliphate in Baghdad. Later, the Sulayhid dynasty (1047–1138) further solidified this connection by establishing a state in Yemen that was nominally subject to the Fatimid caliph in Egypt. Through the efforts of leaders like Ali ibn Muhammad al-Sulayhi, the Sulayhids were responsible for restoring and maintaining Ismaili influence in the region, acting as a regional bastion for the sect amidst competing local powers.12