Al-'Awasim

Al-ʿAwāṣim (, "the defences, fortifications"; sing. al-ʿāṣimah, , "protectress") was the Arabic term used to refer to the Muslim side of the frontier zone between the Byzantine Empire and the Umayyad and Abbasid Caliphates in Cilicia, northern Syria and Upper Mesopotamia. It was established in the early 8th century, once the first wave of the Muslim conquests ebbed, and lasted until the mid-10th century, when the Byzantine advance overran it. It comprised the forward marches, comprising a chain of fortified strongholds, known as al-thughūr (; sing. al-thaghr, , "cleft, opening"), and the rear or inner regions of the frontier zone, which was known as al-ʿawāṣim proper. On the Byzantine side, the Muslim marches were mirrored by the institution of the kleisourai and the akritai (border guards).

The term thughūr was also used in the marches of al-Andalus and Transoxiana, and was revived by the Mamluk Sultanate in the 14th century, when the areas traditionally comprising the ʿawāṣim and thughūr in the northern Syrian region and Upper Mesopotamia came under their control.