In 1728 or 1731 the chief representative of Lahej declared himself an independent Sultan in defiance of the Qasimid Dynasty and conquered Aden thus establishing the Sultanate of Lahej. In 1740 the 'Abdali sultan of Lahej became completely independent.[20] It became independent thanks to the fracturing of the Zaidi State in north Yemen.[21] The Sultanate of Lahej became an independent entity, from 1728 to 1839.