Topping a low hill, circled by walls and culminating in a tapering minaret, the qsar (pl. qusūr) is the castle of the Sahara. They are found between southern Morocco and Siwa in Egypt, and range in size from tiny defended buildings to large towns of over 25ha. In this book, Chekhab-Abudaya examines a subset of these structures, those of south-west Algeria, where the towns of the Mzab inspired Le Corbusier's Notre Dame du Haut at Ronchamp. The book combines a detailed discussion and well-illustrated catalogue of the chosen sites with a long historiographical analysis of the class. The author skilfully dismisses a number of easy oppositions—between nomads and sedentary occupation (or semi-nomadic and semi-sedentary occupation)—and takes a holistic view of the oasis culture of the Sahara, balancing the ecological constraints with those deriving from its very specific history.

The question of their origin and distribution is interesting, and has been treated by scholars for over a century. Chekhab-Abudaya treads carefully through this abundant bibliography, quoting at length rather than paraphrasing. What is not entirely clear is her own point of view. Even though the conclusion of her analysis is entitled ‘Le qsar, forme d'urbanisme du dār al-Islām’, she does not actually argue that its origins are Islamic; indeed, she is well aware of the work of David Mattingly in the Fezzan, where numerous pre-Islamic qusūr are found. This could have been pushed much further by citing the work of the UNESCO Libyan Valleys Survey, which identified large numbers of square, fortified, courtyard buildings constructed from the third century AD onwards, and clearly related to the Roman quadriburgia (Barker et al. Reference Barker, Gilbertson, Jones and Mattingly1996). The fact remains, however, that there is more to it than that: multiple influences are at play. Here, the absence of the Libyan bibliography is an issue; recent work by the University of Rome La Sapienza has resulted in the publication of two major prehistoric sites, Aghram Nadhariff and Fewet, where the circular defensive walls are created by the exterior walls of the houses, arranged concentrically just as they are in the Mzab (Liverani Reference Liverani2005; Mori Reference Mori2013). Chekhab-Abudaya's ignorance of the Italian work in Libya is a general problem, particularly when that of Barbara Barich is omitted from the prehistoric summary—but then publications on the rest of the Maghreb are regularly ignored in Libya.

The internal layout of the qusūr, with their dendritic structures and complex zoning by family, is clearly related to other ‘Islamic cities’ (a concept the author rightly distrusts), while the form of the houses with their square patios derives from Arabian models. The position of the market at the periphery of the qsar is, however, very Berber (or Amazigh): the market, as a place where external people can penetrate the town, is regarded as potentially polluting, and in the Kabylie region, markets are usually placed entirely outside the settlements.

The most interesting observation Chekhab-Abudaya draws from her material is the clear distinction between the Ibadi settlement of the Mzab, where the mosque is found at the heart of the town, its minaret the highest point, and those qusūr where a defended qasba acts as the keep in a castle, a built expression of seigneurial power. In contrast, in the Ibadi towns of the Mzab, there is no apparent hierarchy, and a complex legal code stops any building from dominating its neighbour. This is characteristically Amazight: a cultural code of equality between families played out in the built environment. Fission, rather than hierarchy, is the standard response to conflict. In the Mzab, it resulted in five separate qusūr (and a World Heritage Site). In this sense, we may see the way in which Amazigh culture influenced Kharijism: while the original capital of the Ibadis at Tihert (north-west Algeria) had a building plausibly interpreted as the qasba of its founder, Ibn Rustum, by the time Ibadis settled Jerba (Tunisia) and the Mzab, such constructed representations of power seem to have entirely disappeared.

Teasing out the separate strands of influence that created the Saharan qusūr is hardly an easy task, and with the exception of the eleventh-century foundations in the Mzab, firm chronological data are absent. Chekhab-Abudaya rightly sees the expanding concentric circles with radial streets that characterise the plans of many of the qusūr as the result of a series of new arrivals, settling outside the walls and then building new ones. She contrasts these concentric plans with those that contain rough grids, which she judges to be later. But none of these is easily dated. No excavations have ever taken place (except in the deserted Ibadi town of Sedrata) and, to my knowledge, no radiocarbon dating has been carried out on a qsar outside Libya (although radiocarbon dates for the qusūr of the Wadi Draa in Morocco are underway; Corisande Fenwick pers. comm.). Chekhab-Abudaya's investigation thus serves the very useful purpose of pulling together all the available information, creating numerous and beautifully clear comparative plans, and asking a series of questions that certainly remain to be answered. New data could, and should, come from future archaeological work on these sites and, indeed, on the whole of the northern Sahara.