 On the evening of 22 May 1844 , Siyyid `Alí @-@ Muhammad of Shiraz , Iran proclaimed that he was " the Báb " ( الباب " the Gate " ) , referring to his later claim to the station of Mahdi , the Twelfth Imam of Shi`a Islam . His followers were therefore known as Bábís . As the Báb 's teachings spread , which the Islamic clergy saw as a threat , his followers came under increased persecution and torture . The conflicts escalated in several places to military sieges by the Shah 's army . The Báb himself was imprisoned and eventually executed in 1850 . 
