In this short but incisive book, Simon Barton makes a compelling case for the interpretation of interfaith sexual liaisons between Christians and Muslims in medieval Iberia as an element of power politics and a crucial factor in the strengthening of community identity and the establishment of social and cultural boundaries between the two religions. The subject of interfaith relations in medieval Iberia has received considerable scholarly attention over the last couple of decades, but the extent to which sex, power and identity were bound together and shaped those relations has remained something of a blind spot. Barton's book fills precisely this gap in the literature, complementing the work that has been done in recent years by, amongst others, David Nirenberg, Maribel Fierro and Brian Catlos. The story it tells is essentially one of power, of political and ideological domination, and at its centre there are women: real and symbolic women, exploited by power plays and morality plays, the constant focus of anxieties about sex with the Other.

In the first chapter, Barton shows that during the period of Muslim hegemony in the peninsula, between the eighth and eleventh centuries, but particularly sharply right after the invasion in 711, conquerors and conquered resorted to interfaith marriage and slave concubinage as a means of obtaining political and economic advantages. For the new Muslim lords, they provided easy access to the landed wealth of Visigothic magnates; for many of the latter, they were a way of adjusting to the new political order while strengthening their local autonomy. In the matter of interfaith relations, therefore, political expediency seems to have prevailed over religious warnings about the serious danger that young Muslim boys and girls might have been corrupted by the deep-seated Christian faith of their converted mothers. As Barton rightly points out, however, laying claim to Christian women – those ‘herds of fat gazelles’ in Ibn Darraj's words – was also (perhaps primarily) a propaganda weapon and a form of psychological warfare, the goal of which was to impress on the minds of Christian men the completeness of Muslim victory and domination.

The waning of the latter in the eleventh century and the gradual shift in the balance of power in favour of the Northern Christian kingdoms brought with them a radical transformation of the dynamics of interfaith relations between Christians and Muslims. This transformation and its subsequent development until the end of the fifteenth century are the object of the three remaining chapters of the book. From the twelfth century onward, secular and religious authorities in the Christian kingdoms began to restrict interfaith sex and to establish rules to regulate intimacy, which we find variously expressed, for example, in municipal fueros and Alfonso x's Siete Partidas, which form the documentary basis of chapter ii. Barton suggests two explanations for why this happened in the twelfth and thirteenth centuries instead of earlier: the changing demographics of the Christian kingdoms, as a consequence of rapid territorial expansion and the incorporation of important Muslim and Jewish communities; and the influence of external cultural forces, such as the preaching of the crusade, the formulation of a theological ‘discourse of exclusion’ within the Church and its dissemination across the peninsula by the agents of papal authority: papal legates, French prelates and papal councils. Although all these factors doubtless contributed towards moulding Christian attitudes to interfaith sex in twelfth- and thirteenth-century Iberia, for the simple reason that earlier sources do not tell us exactly how Christian authorities felt about the matter, the fundamental cause of the change after 1100 (other than the wider shift in the balance of power) remains unclear. But assuming that there was indeed a change, surely the anxiety of religious and secular authorities over interfaith sex in the twelfth century was not entirely unrelated to the formulation of the Church's doctrine on marriage at about the same time and the resultant assertion of its right to regulate the sexual lives of the laity, a connection that might have been well worth exploring.

In chapters iii and iv Barton looks at representations of interfaith liaisons in historical and hagiographical narratives and poetical works, highly biased and problematic writings in which Iberian history since the last of the Visigoths was refashioned and reinvented to suit the political and ideological needs of the day. One such writing, purporting to date from the ninth century but actually one of the finest examples of twelfth-century Compostelan forgeries, tells the story of the tribute of the hundred maidens, an entirely fictional offering which Christian rulers in the north supposedly made every year to their Muslim enemies. According to the Compostelan forgery, it was King Ramiro i's refusal to pay the tribute which led to the Battle of Clavijo, which led in turn to St James's providential intervention and the miraculous Asturian victory, which in turn led to the creation by a thankful Ramiro of the Voto de Santiago, an extraordinary (and all too real) tax payable by all parishes across Iberia to the church of Compostela. Barton gives particular prominence to this twelfth-century marketing stunt, and rightly so, for it created one of the most enduring topoi of interfaith sex in late medieval and early modern Iberian literature; Barton stitches together its many and intricate variations with skill and elegance. As he points out, the story of the tribute of the hundred maidens, which linked Christian identity and power to the sexual purity and honour of Christian women, attributing the loss of the latter to male pusillanimity, was as much a story of dishonour, pollution of society and corruption of the faith as it was one of male failure. The relationship between sex, power and cultural identity is also the common thread that runs through the legends and literary tropes analysed in chapter iv, in which interfaith relations between Christian men and Muslim women are presented as symbolic acts of Christian conquest and Muslim surrender, and the triumph of love equated with the triumph of the Christian faith. Permissible interfaith relations were, in the eyes of Christian authorities, one-way relations, of course, our men with their women, just as they had been in the Al-Andalus, when Muslim rule had been dominant. The gradual realisation of this symmetry is not the least of the many pleasures to be derived from this intelligent and insightful book.