A Persian mathematician and astronomer born in Nayriz (present-day Fars province, Iran), Al-Nayrizi (Latin: Anaritius) worked in Baghdad under Caliph al-Mu'tadid. His most influential contribution was an extensive commentary on Al-Hajjaj's Arabic translation of Euclid's Elements, incorporating unique extracts from two now-lost Greek commentaries (Hero of Alexandria, Simplicius of Cilicia), offering a proof of the Pythagorean theorem and an attempted proof of the parallel postulate.