Bāb, a high rank in the daʿwa organisation and religious hierarchy (ḥudūd al-dīn) of the Ismailis. The hierarchical organisation of the Ismaili daʿwa and the functions of its different ranks were always important but secret and obscure aspects of the Ismaili movement. Ismaili works generally maintain silence on the subject because of the esoteric and often secretive nature of the Ismaili daʿwa. The enmity of many Sunni emirs, rulers and religious scholars generally obliged the Ismailis to conduct their daʿwa activities in utmost secrecy (except within the dominions of the …