Abu al-Qasim Mahmud ibn Umar al-Zamakhshari was a medieval Muslim scholar of Iranian descent. He travelled to Mecca and settled there for five years and has been known since then as 'Jar Allah'. He was a Mu'tazilite theologian, linguist, poet and interpreter of the Quran. He is best known for his book Al-Kashshaf, which interprets and linguistically analyzes Quranic expressions and the use of figurative speech for conveying meaning. This work is a primary source for all major linguists.