Islam was first introduced into Africa by the Arab army that invaded Egypt under the command of ʻAmr b. al-ʻĀṣ in A.D. 640. Three years later the withdrawal of the Byzantine troops abandoned the vast Christian population into the hands of the Muslim conquerors. The rapid success of the Arab invaders was largely due to the welcome they received from the native Christians, who hated the Byzantine rule not only for its oppressive administration, but also—and chiefly—on account of the bitterness of theological rancour. The Jacobites, who formed the majority of the Christian population, had been very roughly handled by the Orthodox adherents of the court and subjected to indignities that have not been forgotten by their children even to the present day. [264] Some were tortured and then thrown into the sea; many followed their Patriarch into exile to escape from the hands of their persecutors, while a large number disguised their real opinions under a pretended acceptance of the Council of Chalcedon. [265] To these Copts, as the Jacobite Christians of Egypt are called, the Muhammadan conquest brought a freedom of religious life such as they had not enjoyed for a century. On payment of the tribute, ʻAmr left them in undisturbed possession of their churches and guaranteed to them autonomy in all ecclesiastical matters, thus delivering them from the continual interference that had been so grievous a burden under the previous rule; he laid his hands on none of the property of the churches and committed no act of spoliation or pillage. [266] In the early days of the Muhammadan rule then, the condition of the Copts seems to have been fairly tolerable, [267] and there is no evidence of their widespread apostasy to Islam being due to persecution or unjust pressure on the part of their new rulers. Even before the conquest was complete, while the capital, Alexandria, still held out, many of them went over to Islam, [268] and a few years later the example these had set was followed by many others. [269] In the reign of ʻUthmān (A.D. 643–655), the revenue derived from Egypt amounted to twelve millions; a few years later, in the reign of Muʻāwiyah (661–679), it had fallen to five millions owing to the enormous number of conversions: under ʻUmar II (717–720) it fell still lower, so that the governor of Egypt [270] proposed that in future the converts should not be exempted from the payment of the capitation-tax, but this the pious caliph refused to allow, saying that God had sent Muḥammad to call men to a knowledge of the truth and not to be a collector of taxes. [271]