Jār Allāh Maḥmūd b. ʿUmar al-Zamakhsharī was an important Muʿtazilī theologian. He was principally known for his mastery of the Arabic linguistic sciences. Zamakhsharī hailed from the region of Khwārazm, born in the small town of Zamakhshar in the year 467/1075. His religious education began in his hometown. He first memorized the Qurʾān under the auspices of his father, then traveled to the capital of Khwārazm, al-Jurjāniyya, to work as a scribe and to continue his studies. He studied with Abū ʿAlī al-Ḥasan b. al-Muẓaffar al-Naysābūrī, and then with Abū Muḍar Maḥmūd b. Jarīr al-Ḍabbī al-Iṣfahānī (d. 507/1114). The latter was also his patron and an important source for his ardent Muʿtazilism. In Khwārazm, he also had relations with the well-regarded Muʿtazilī theologian Rukn al-Dīn Ibn al-Malāḥimī (d. 536/1141). Zamakhsharī traveled to Bukhārā during this period to learn ḥadīth. In an effort to secure funding, he wrote poetry and eulogies for the leading men of his time, most importantly the Seljuk vizier Niẓām al-Mulk. After falling ill in the year 512/1118, he vowed to lead an ascetic life away from political patronage. He visited the eastern Islamic world, first Baghdad, where he met the Ḥanafī jurist Aḥmad b. ʿAlī al- Dāmghānī and the learned grammarian Hibat Allāh Ibn al-Shajarī. He then made his way to Mecca, where he was welcomed by the amīr of Mecca, Ibn Wahhās (d. 526/1131), a Zaydī-Muʿtazilī who hosted Zamakhsharī in Mecca during his many stays. His first stay was for a period of two years, after which he returned to Khwarāzm. He then set out for Mecca again and again was received by Ibn Wahhās. He stayed for a period of three years beginning in 526/1132. Ibn Wahhās encouraged him to complete his Qurʾān commentary al-Kashshāf in Mecca in the year 528/1133. He returned to Mecca for a third visit in 533/1138. Zamakhsharī died in al-Jurjāniyya in 538/1144. Due to his many visits to Mecca, he gained the sobriquet Jār Allāh, “the neighbor of God.” His most important scholarly contributions were in Arabic philology and grammar (naḥw). These include the Kitāb al-Mufaṣṣal fī l-naḥw. At least twenty-four commentaries were written on the work, the most famous being that of Ibn Yaʿīsh (d. 643/1245), under whom the reputed grammarian Jamāl al-Dīn Ibn Mālik studied in Damascus. Zamakhsharī’s Qurʾān commentary al-Kashshāf also garnered widespread fame, being perhaps his most well-known work, with dozens of commentaries and super-commentaries in later centuries.