After the Islamic conquest of Persia, Jews, along with Christians and Zoroastrians, were assigned the status of dhimmis, inferior subjects of the Islamic empire. Dhimmis were allowed to practice their religion, but were forced to pay taxes (jizya, a poll tax, and initially also kharaj, a land tax) in favor of the Arab Muslim conquerors, and as a compensation for being excused from military service and payment of poor tax incumbent on Muslims.[27] Dhimmis were also required to submit to a number of social and legal disabilities; they were prohibited from bearing arms, riding horses, testifying in courts in cases involving a Muslim, and frequently required to wear clothes that clearly distinguished them from Muslims.[citation needed] Although some of these restrictions were sometimes relaxed, the overall condition of inequality remained in force until the Mongol invasion.[28] The 10th-century Persian historian Estakhri reports that :