By the time of Diocletian the transition upon the Arabian limes from camp to fortress had been completed. The Umayyad khalifs, when they in turn strewed the fringes of the Syrian desert with the creations of their architects, copied, not the Roman plan which had been imported under Trajan and had survived, in broad outline at any rate, at least, as late as the year A.D. 162 (the date of Ḍumair), they copied its oriental counterpart, adapting it to the use of princes by methods borrowed from Byzantium and from Persia. We know that the Umayyads, like the Ghassânids before them, repaired and re-occupied the Roman fortresses. Hamza al-Iṣfahâni believed that Qasṭal and Odhruh had been built by Djabala ibn al-Ḥârith;[243] Yâqût mentions that Yazîd ibn ‘Abd al-malik (Yazîd II) lived at Muwaqqar, and judging from the existing remains it is probable that he either built or rebuilt it.[244] His son Walîd occupied Qastṭal and Azraq.[245] But princes whose passion for magnificent construction was so great that the subjects of Yazîd III could see cause for exacting from him, when he came to the throne, a promise that he would not lay stone to stone or brick to brick,[246] were not likely to content themselves with the forts of the Roman limes. The poets, who were welcome guests at their palaces in the wilderness, have left descriptions of the luxury of their surroundings,[247] and the picture has been completed by the discovery of some of the buildings themselves. None of the ruins which have been examined are mentioned by contemporary writers under the name by which they are known to the Beduin, but a palace or palaces are recorded in the Wâdi Ghadaf, and it is in that district that Ṭûbah, Kharâneh, and Qṣair ‘Amrah stand.[248] Mshattâ, which was the first to be visited by archaeologists, bears a name which is probably modern.