It was not always clear that the Arab-Muslims would be successful against the Byzantines and the Persians, the last empires of antiquity. Nonetheless, starting in 634 and continuing into the early eighth century, they found enormous success conquering much of the territory around the Mediterranean basin and central Asia, going as far west as Spain and Portugal and all the way to the Indus River valley in the east. The new Islamic state, or caliphate (an area under the control of a caliph), was larger than the realm of Alexander the Great, the Romans, or the Han Chinese; it was the largest empire the world had yet seen (Figure 11.13). Figure 11.13 This map shows the extent the new Islamic caliphate had achieved by the end of its first dynasty, the Umayyads. During the eighth century CE, the Umayyads ruled the world’s largest empire. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license) The crucial early years of Islamic expansion were overseen by the first four caliphs, a group of rulers who came to be called the “rightly guided” or Rashidun. These four figures—Abu Bakr, Umar, Uthman, and the originally overlooked son-in-law of Muhammad, Ali—ruled between 632 and 661, a period when much Byzantine and Persian territory was conquered, and the message of Islam spread throughout a predominantly Christian Middle East. While the Byzantines and the Persians had employed the Arabian Ghassanids and Lakhmids to guard their borders and serve in their wars, the arrival of the Arab-Muslim armies was unlike anything either empire had seen before. The Byzantine emperor Heraclius, heralded for bringing victory over the Persians, was not able to enjoy his triumph for very long. Meanwhile, defeated Sasanian Persia was coping with the effects of a destabilizing civil war. The ruler who ultimately emerged in 632, Yazdegerd III, was little more than a puppet king, a child figurehead, and the once-unified Sasanian state devolved into a fractured entity ruled by the noble families. Link to Learning This brief audio essay from BBC Sounds discusses the development of the Arab-Islamic conquests and their long-term successes. The Arab-Muslim armies began their invasion with the provinces of Iraq and Syria before moving eastward into the Iranian plateau and westward into Egypt. On all fronts, the first decades of the conflict proved extraordinarily successful for the conquerors. Shortly after winning several skirmishes and capturing the Syrian city of Damascus, the Arab-Muslims bested the Byzantine army at the Battle of Yarmuk in 636. Unable to defend the remaining cities of the region, the Byzantines then abandoned Greater Syria, consisting of what are today Israel, Jordan, Lebanon, Palestine, and Syria. The Arab-Muslim armies continued northward and westward, laying siege to and capturing the Egyptian port city of Alexandria in 641. Many other Byzantine provinces soon followed. In Iraq, the armies of Persia lost to the Arab-Muslims at the Battle of Qadisiyya, bringing an end to any sustained resistance by the Persians. Still, the conquest of Persia proved to be a longer-term process. Sasanian-controlled territory was vast and geographically diverse, and the independence the Sasanian nobility had wrested from the central government following the war with the Byzantines meant the Arab-Muslims needed to negotiate with many local governors and landed elites for the surrender of their territory. At the same time, dynamics between the Sasanian nobility and the lower classes had already begun changing. The nobility existed in a well-established court culture and practiced the traditional Persian religion of Zoroastrianism. Outside this elite circle, however, Zoroastrianism had long been declining in popularity, while other religious traditions, including Nestorian Christianity and Manichaeism, grew. The collapse of the Sasanian ruling family in Persia also provides a unique glimpse into something that had not happened among the elite before: the brief rise of a female ruler, Boran. The daughter of Khosrow II, Boran came to power briefly during the civil war after the Byzantine victory over her father. While such opportunities for female power in the region were few and far between, her rule underscores that seventh-century Persia was already a state and a people in transition, and the arrival of the Arab-Muslims with the cultural practices of Arabia and the religion of Islam only expedited change. Although the Byzantines and Persians had put up resistance, by the 650s much of their territory had been taken by the new Islamic state of the Rashidun. Heraclius died in 641, with the territories he and the Byzantines had fought to retake from the Persians largely lost. The Byzantine Empire survived the Arab-Muslim conquests, but it never again controlled much of the territory of the old Roman east. The Sasanian ruler Yazdegerd III fled east to escape capture by the Arab-Muslims or their supporters, spending much of his short life on the run before being killed by his own people in 651. By that time, the entirety of the Persian Empire had effectively been brought into the control of the new Islamic state.