أحمد بن يحيى
Ahmad bin Yahya was born in Medina (present-day Saudi Arabia) as the son of the later imam al-Hadi ila'l-Haqq Yahya and Fatimah bint Al-Hasan. In 897 he followed his father and his brother Muhammad to Yemen, where al-Hadi was acknowledged as the first imam of the Zaydiyya branch of Shi'a Islam in Yemen. By 907 he was assisting his father as military commander. After a sojourn in Medina he returned to the Zaidi capital in Yemen, Sa'dah, where he was chosen to succeed his brother al-Murtada Muhammad in September 913. Al-Murtada had abdicated in 912 under somewhat unclear circumstances, and seemingly supported the appointment of Ahmad. The new imam took the honorific title an-Nasir Ahmad. He was considered an efficacious ruler; one of his adherents composed a panegyric text which described the imam as the one who strengthened Islam after it had become weak.