Khan's date of birth has not been recorded. According to historian Ashirbadi Lal Srivastava, Khan was born in and his birth name was Mir Muhammad Amin. His father was Mir Muhammad Nasir, a merchant in Khorasan. Khan had one elder brother, Mir Muhammad Baqar. One of their ancestors was Mir Shamsuddin, a "sayyid" (descendant of Muhammad) and a "kazi" (Islamic judge) in Nishapur. He was a twenty-first-generation descendant of Musa al-Kadhim, the seventh imam of Shia Islam. No historian has recorded any events in Khan's early life.