Abū-Bakr Muḥammad ibn Yaḥyā ibn al-Sāyigh ibn Bājja, the Islamic philosopher, was known to the medieval Scholastics as Avempace. He was born in Saragossa at the end of the fifth century AH, eleventh century CE, and died in Fez, Morocco, in 533 AH/1138 CE. During his brief life he endured the tribulations occasioned by the Christian "reconquest" of Andalusia. It is known that he wrote several commentaries on Aristotle's treatises and that he was very learned in medicine, mathematics, and astronomy. He was involved in the quarrel initiated by the Peripatetics, during which al-Bītrogī, whom the Scholastics called Alpetragius, distinguished himself. Ibn Bājja opposed his own hypotheses to Ptolemy's system.

Ibn Bājja's philosophical works have remained incomplete, notably the treatise that gained him his reputation, Tadbīr al-motawaḥḥid...