Abu'l-Fath was a
Sayyid but not a member of the dynasty of the
Rassids. He traced his descent from Zaid bin al-Hasan bin Ali, grandson of the
caliph Ali. He was born and raised in
Deylaman south of the
Caspian Sea where there was also a
Zaydiyyah congregation, hence his cognomen ad-Dailami. Abu'l-Fath arrived to Yemen in 1038 or later, and claimed the
Zaidi imamate. In 1046 the tribesmen of
Hamdan accepted him, and he was able to seize
Sa'dah and
San'a in the same year. The new ruler set out to organize the Yemeni highland, appointing officials and collecting land taxes and
zakat. As his permanent residence, he used a fortified mountain near Dhibin. In 1047 several further highland groups submitted to Abu'l-Fath, including the emir Ja'far, brother of imam
al-Mahdi al-Husayn and leader of the Husayniyya Zaidi sect. ==Sulayhid victory==