Analysis of information sources in references of the Wikipedia article "Yusuf ibn Tashfin" in English language version.
his mother was Lemtouna ... Fathma bent Syr son of Yhya ben Ouaggag ben Ouartakthyn
They then paid obedience to the caliph in Baghdad as Prince of the Believer (amir al mu'minin), inventing for themselves the lesser title of Prince of the Muslims (amir al-muslimin)