Initially, after the first Muslim conquests in the 7th century, "kharaj" usually denoted a lump-sum duty levied upon the conquered provinces and collected by the officials of the former Byzantine and Sasanian empires, or, more broadly, any kind of tax levied by Muslim conquerors on their non-Muslim subjects, dhimmis. At that time, "kharaj" was synonymous with "jizyah", which later emerged as a poll tax paid by dhimmis. Muslim landowners, on the other hand, paid only ushr, a religious tithe, which carried a much lower rate of taxation.