His father was the imam al-Mansur al-Qasim al-Iyyani who briefly held power in the Yemeni inland in 999–1002, and died in 1003.
After the death of al-Mansur, al-Husayn set forth his claim to the imamate, in rivalry with his distant relative ad-Da'i Yusuf.
At this time, the key city San'a was governed by the Zaidi sharif al-Qasim bin al-Husayn.
After his demise, his brother Ja'far played a political role as emir in the Yemeni highlands for several decades.
He established himself in the impenetrable stronghold Shahara and was the main opponent of the Sulayhid dynasty in the second half of the eleventh century.