After he had lost the city for good, he withdrew to Sa'dah in the north, which was the old stronghold of the Zaydiyyah.
Al-Qasim invaded Yemen in 997 or 998 and appropriated Sa'dah, the traditional capital of the Zaydiyyah domain.
A Caspian Zaidi leader in Persia, Abu Talib Yahya, is sometimes formally counted as imam in the period 1020-1033 in Zaydiyyah historiography.
Nevertheless, the people of the traditional centre of the Zaydiyyah community, Sa'dah, refused to support him and instead proclaimed al-Hadi Izz ad-Din.