evidence: Isolated in the Syrian desert, Qasr al-Hayr al-Sharqi stands approximately 97 km to the northeast of Palmyra and 64 km to the south of Rusafa. It was originally constructed by 728-9 under the caliph Hisham to be used as a retreat for the Umayyad caliphate. However after their decline in regional authority, the site was absorbed and embellished by the Abbasids under caliph Harun al-Rashid and remained functional until the 14th century. [...] Qasr al-Hayr al-Sharqi displays influences in construction from Syria and Iraq, in the breadth of its masonry work and in the use of brick throughout the complex, respectively. [...] Grabar, R. Holod, J. Knutstad and W. Trousdale. A City in the Desert: Qasr al-Hayr East. USA: Harvard Middle Eastern Monographs, 1978.