 All of Khorasan was soon conquered by the Arabs, who would use it as a base to attack Transoxiana.The death of Yazdegerd thus marked the end of the last pre-Islamic Iranian empire after more than 400 years of rule.An empire–which had a generation earlier briefly conquered Egypt and Asia Minor, even reaching as a far as Constantinople, fell to a force of lightly equipped Arabs that were used to skirmishes and desert warfare.