Abu ’l-Ḥasan ʿAlī b. ʿUthmān b. ʿAlī al-Ghaznawī al-Jullābī al-Hujwīrī , known as ʿAlī al-Hujwīrī or al-Hujwīrī for short, or reverentially as Shaykh Syed ʿAlī al-Hujwīrī or as Dātā Ganj Bakhsh by Muslims of Pakistan and India was an 11th-century Iranian Sayyid Sunni Muslim mystic, theologian, and preacher from Ghazni, who became famous for composing the Kashf al-maḥjūb , which is considered the "earliest formal treatise" on Sufism in Persian. Ali Hujwiri is believed to have contributed "significantly" to the spread of Islam in South Asia through his preaching especially in the Punjab, with one historian describing him as "one of the most important figures to have spread Islam in South Asia."In the present day, Ali Hujwiri is venerated as the patron saint of Lahore, Pakistan by the traditional Punjabi Sunni Muslims of the area. He is, moreover, one of the most widely venerated saints in the entire Indian subcontinent, and his tomb-shrine in Lahore, popularly known as Data Darbar, is one of the most frequented shrines in South Asia. At present, it is Pakistan's largest shrine "in numbers of annual visitors and in the size of the shrine complex," and, having been nationalized in 1960, is managed today by the Department of Awqaf and Religious Affairs of the Punjab. The mystic himself, remains a "household name" in the daily Islam of both India and Pakistan. In 2016, the Government of Pakistan declared 21 November to be a public holiday for the commemoration of the commencement of Ali Hujwiri's three-day death anniversary.