Kushāf, situated near the confluence of the Great Zāb with the Tigris, has been identified with the Old Babylonian and middle to Neo-Assyrian town of Kaštappum/Kaltappu/Kassappa, whose great strategic importance is reflected in the Assyrian sources.
Kushāf must have maintained some urban institutions until the beginning of the thirteenth century, when the place was still able to attract a Muslim scholar to live and be buried there. Later, the citadel at Kushāf was mentioned several times as one of the Ilkhanid power bases and even later, still in use, in the beginning of the 19th century.
According to the survey, the town had a tripartite structure. A triangular shaped citadel (2.2 ha), fortified with an enceinte wall and ditch, was complemented by lower town area (9.7 ha), which itself was in an elevated location.
A large, dispersed, organically developed settlement (108 ha), probably from the early Islamic period, emerged in the plain at the south forefront of the stronghold. The citadel´s south gate was fitted with a massive avant-corps or barbican, built partly from rusticated limestone ashlars, which links the building to the Frankish, Ayyubid, or early Mamluk architecture of Bilād al-Shām.