Muslim sources, frequently confirmed by the unintentional witness of contemporaneous Greek and Syriac writers, make it clear that the Arabs came surging out of the Arabian peninsula in the seventh century, with the initial attack on Damascus in 635, Ctesiphon in 637, and Jerusalem in 638. Syria gradually fell into Arab hands, with the Battle of Yarmuk in 636 inflicting a crushing defeat on the Byzantine army. The capital of the empire was moved from Syria to Baghdad, and the action provided the pretext for the splintering of governance and power in various areas. During the rule of the Umayyad caliph Abd al-Malik, an event of major significance took place; the Dome of the Rock in Jerusalem was built. The Dome of the Rock embodies the arrival of nascent Islam and underlines the religion's rising presence. The institution of the caliphate was defined as having the responsibility for maintaining and implementing the ordinances of Muslim law.