Shah Wali Ullah was an 18th century Islamic scholar born in 1703 in Delhi who led religious reforms among Muslims in South Asia. He established madrassas to spread Islamic teachings, translated the Quran into Persian, and worked to unite divided Muslim sects. His teachings emphasized a return to pure Islamic principles and helped revive Islam in the subcontinent during a period of political chaos and decline of the Mughal empire. He sent missionaries across regions to spread his message and wrote over 50 books explaining Islam. His emphasis on religious education and unity among Muslims inspired later reformers and contributed to the preservation of Islam in the region.