 Sufis also used it to intensify their mystical experience and to facilitate a sense of union with God.The earliest known documented description of khat is found in the "Kitab al-Saidala fi al-Tibb" , an 11th-century work on pharmacy and materia medica written by Abū Rayhān al-Bīrūnī, a Persian scientist and biologist.Unaware of its origins, al-Bīrūnī wrote that khat is