The Imams of Yemen, later also titled the Kings of Yemen, were religiously consecrated leaders belonging to the Zaidiyyah branch of Shia Islam. They established a blend of religious and temporal-political rule in parts of Yemen from 897. Their imamate endured under varying circumstances until the end of the North Yemen Civil War in 1970, following the republican revolution in 1962. Zaidiyyah theology differed from Isma'ilism or Twelver Shi’ism by stressing the presence of an active and visible imam as leader. The imam was expected to be knowledgeable in religious scholarship, and to prove himself a worthy headman of the community, even in battle if this was necessary. A claimant of the imamate would proclaim a "call" (dawah), and there were not infrequently more than one claimant.
History
Establishment
The imams based their legitimacy on descent from the Islamic prophet Muhammad, mostly via al-Qasim ar-Rassi (d. 860). After him, the medieval imams are sometimes known as the Rassids. The first of the ruling line, his grandson al-Hadi ila'l-Haqq Yahya, was born in Medina. His fame as an intellectual as well as a leader of note, led to his invitation to Yemen. He was summoned to govern the highland tribes in 893 and again in 896–97. Al-Hadi introduced a multitude of policies and practices that evolved into the particular Yemenite Zaidiyyah brand. The efforts of al-Hadi eventually became the basic guidelines for the religious as well as political characteristics of Yemeni Zaydism. Al-Hadi, however, was not able to consolidate his rule in all of Yemen. He could not even create an enduring state in the highlands, due to the strong localism persisting in the region. There were revolts as well as segments of the population that did not accept his and his successors' pretensions to religio-political rule.
Although he did not succeed in establishing any permanent administrative infrastructure, al-Hadi's descendants, and other Alid clans who arrived in his company, became the local aristocracy of the northern highlands. It is from among them that the imams of Yemen were selected for the next one thousand years. The imams were usually chosen from the offspring of al-Qasim ar-Rassi and more specifically of al-Hadi, but on at least eight occasions they were picked from other lines descending from Muhammad's grandsons Hasan and Husain.
Yemen throughout most of that period was only rarely a unified political entity; in fact, what has included within its frontiers varied widely, and it has not been governed consistently or uniformly by any single set of rulers except for brief periods. It existed as a part of a number of different political systems/ruling dynasties between the ninth and sixteenth centuries, after which it became a part of the Ottoman Empire.
Rivalries with other dynasties
After Imam al-Hadi's death in 911, his sons took over the imamate in turn, although it was not hereditary but rather elective among the descendants of Muhammad. From the eleventh to the early seventeenth centuries, however, the imams were usually not chosen from the sons of the former imam, but the title rather circulated among the various Rassid branches. Meanwhile, a multitude of smaller dynasties and families established themselves in the highlands, as well as in the Tihamah (the low coastal plain) where the imams rarely gained influence. Among the better known of these are the Yu'firids (847–997), the Najahids (1021–1158), the Sulayhids (1047–1138), the Zuray'ids (1080–1174), and the Hatimids (1098–1174). It was during this period, when the Fatimid Caliphate was influential, that a portion of the population was converted to Isma'ilism.
Beginning with the conquest of Yemen by the family of Salah ad-Din ibn Ayyub (Saladin) in 1174, a series of dynasties exercised a modicum of control and administration in Yemen for roughly the next 400 years; these are, in chronological sequence, the Ayyubids, from 1174 to 1229; the Rasulids, from 1229 to 1454; the Tahirids, from 1454 to 1517; and the Mamluks, from 1517 to 1538, when the Ottoman Empire took the Tihamah.
During most of this period, the dynasties and their rulers were primarily engaged in familial, regional, and occasionally sectarian disputes. Ironically, the Sunni Rasulids, who eventually concentrated their rule in southern Yemen for precisely that reason, were the dynasty under which the region experienced the greatest economic growth and political stability.