Background
Najm ad-Din Yahya bin Muhsin was a seventh-generation descendant of imam al-Mukhtar al-Qasim (d 956).
Najm ad-Din Yahya bin Muhsin was a seventh-generation descendant of imam al-Mukhtar al-Qasim (d 956).
He ruled from 1217 to 1239, partly in rivalry with a contender. The old imam al-Mansur Abdallah died in 1217 in Kawkaban after many years of inconclusive struggles against the Ayyubids, who established a sub-branch in Yemen in 1173. The latter died from a battle wound in 1226.
Ayyubid rule in Yemen was replaced in 1229 by the Rasulid Dynasty (1229-1254). The first Rasulid Sultan, Nur ad-Din Umar I, seized several places in the highland, such as San'a, Ta'izz and Kawkaban. Al-Hadi Yahya died in 1239 and was buried in Saqayn.
His death was followed by an interregnum of nine years until al-Mahdi Ahmad bin al-Husayn, from another branch of the Rassids, was proclaimed.