There can be no doubt as to the momentous nature of the Arab conquests of the seventh and early eighth centuries. A vast territory stretching from Central Asia in the east to the Iberian peninsula in the west came under the dominion of the Rashidun and Umayyad caliphs. The Arabian peninsula was largely under the control of the Prophet Muhammad before his death in 632, and virtually all of the Byzantine territories of Greater Syria and Egypt were captured by the early 640s. Arab armies went on to besiege the capital of Constantinople for the first time between 674 and 680. The battle of Qadisiyya (635 or 637) marked the beginning of the campaigns against the Sasanian state; by 651 the last shah, Yazdigerd III, was dead and his empire was consigned to history. The conquests continued west into North Africa, with a Muslim expeditionary force led by ‘Uqba ibn Nafi’ which reached the Atlantic Ocean in 680 and with the fall of the key port of Carthage to the Arabs in 697. In 711 an army of Arabs and Berbers crossed the straits of Gibraltar and, later that year, inflicted a decisive defeat over the forces of the Visigothic king, Roderick. To the east the expansion continued into Central Asia, the city of Samarqand coming under Arab control after 710. Not all the campaigns were fought for the acquisition of new land, however; this crucial period of Islamic history was also marked by civil wars (fitna) in 656–61 and 683–92.