It is a poll tax in accordance with

       9:29 "Fight those who believe not in Allah nor the Last Day nor hold that forbidden which hath been forbidden by Allah and His apostle nor acknowledge the religion of truth (even if they are) of the People of the Book until they pay the Jizya with willing submission and feel themselves subdued" 

       The Jizya had to be paid individually at a humiliating public ceremony to remind the Dhimmis (protected people), that they are inferior to the believers, that is, the Muhammadan Muslims.

              This tax was not levied on the People of the Book only, but also on the Zoroasterians, Hindus and Buddhists with similar or more humiliations.

       It must be pointed out, that these taxes, were levied against the original, indigenous inhabitants of the conquered territories, in their own land, as if they were the foreigners, and not the occupying imperialist Arabs.