Mahdids

Their name is derived from their first ruler Ali bin Mahdi who was born in Tihama. Ali bin Mahdi in his turn, traced his ancestry back to the ancient kings of Himyar. He was a religious and wide-travelled figure who performed the hajj every year and met scholars from all over the Muslim world. In 1136–1142 Ali bin Mahdi propagated his religious ideas in the Tihama lowland which at that time was ruled by the Najahids of Zabid. The Najahid queen 'Alam was initially attracted by his teachings and even exempted him and his followers from paying the kharaj. Building up a power base, he gathered an army in 1143 and attacked his benefactors. He made efforts to conquer the town al-Kadrā north of Zabid. This, however, failed. Ali and his followers withdrew to the mountains but were allowed back to the Najahid realm in 1146 at the insistence of queen 'Alam.

Ali bin Mahdi was succeeded by his son Mahdi bin Ali, possibly co-ruling with his younger brother Abd an-Nabi. The sons of Ali consolidated the power relations in the Tihama. An advantageous peace was concluded with the Zurayids of Aden. At the same time the Mahdids attacked other areas in the south such as Lahij and Abyan in order to gain plunder. Mahdi bin Ali died in 1163 and his brother Abd an-Nabi gained full control. He was reputed as an exceedingly strict lord who imposed death penalty for anyone opposing his teachings, and for wine drinking, singing and illicit sexual intercourse (although other sources suggest that he was himself a drunkard and womanizer). He upheld egalitarian principles of common property within the community. Muslim historians usually denounce him as a half-crazed robber with world-ruling ambitions.

Abd an-Nabi carried on the expansive policy of the dynasty, attacking the Sulaymanids in northern Tihama whose territories were annexed. The cities Ta'izz and Ibb fell in 1164 and Aden was besieged in the same year. The Zurayids of Aden allied with the Hamdanid sultan of San'a in 1172. Together they managed to defeat the Mahdid forces in 1173. Abd an-Nabi withdrew to Zabid. Shortly after these events, the Ayyubid prince Turan Shah led an expedition to southern Arabia. One of the motives of the Ayyubids to invade Yemen was reportedly the stance of the Mahdids who were considered heretics and associated by outsiders with the Kharijites. Moreover, they had stopped mentioning the Abbasid caliph in the Friday prayer, making them a legitimate object of conquest. Turan Shah found a willing ally in the Sulaymanids, whose ruler had been slain by the Mahdids nine years previously.