Are the Persian Gulf city-states slave societies?
"The kafala (sponsorship) system binds all low-status migrant workers in the Gulf to their employers. Generally, the kafala system requires the worker to obtain the employer’s permission to travel or leave the worksite to look for other employment. Regulations require a minimum of two years of work for the sponsor (kafeel) before such permission will even be considered. This encourages widespread wage suppression and conspiracies to deny such permission. Such ‘labour bans’ effectively bind the worker to the employer for a long period of time. More significantly, a worker can’t get an exit visa from the government without permission of the kafeel. "