In early 2018, Professor Bernard F. Reilly wrote me a letter inviting me to collaborate with him to complete his latest academic project, a book tentatively titled Fernando I and the Resurgence of Christian Iberia, 1037-65 [Fernando I and the resurgence of Christian Iberia, 1037-65]. In the letter, he expressed his firm opinion that Fernando was a traditional king of the Asturian line, much more concerned with the Iberian northwest than the Castilian plateau. These ideas remain central to the book, which I have retitled The Kingdom of Leon-Galicia under King Fernando I and Queen Sancha (the role of royal women in the monarchy was profoundly important). It was a composite monarchy, and its diffuse geographical plurality is reflected in the way in which the diplomas list the various regions in which the aforementioned monarchs exercised power: León, Castile or Galicia. In this period, the rule of Castile—by no means inevitable—was still far in the future. Castile was a complex and ambivalent border area: a 'satellite' region on the margins of the Leonese kingdom. On the contrary, places that are often imagined today as peripheral occupied a central role: among them was Galicia, an expansive kingdom that included portuguese, the area between the Douro and the Miño, fully integrated into the Galician kingdom.

These reflections are of basic importance to the way we deal with the borders of the kingdom. According to traditional 11th-century narratives, Leonese rulers were able to exert increasing sway over the kingdoms ta'ifa. It is often stated that as a result of this domain, Fernando was able to extort the so-called payments from pariah, supposedly imposing tributes through his military superiority: a "protection racket" that would be put into practice again in the reign of Alfonso VI. However, the evidence for this is surprisingly thin. Historians of medieval Iberia run the risk of interpreting the eleventh century teleologically, seeing everywhere signs of religious war and the crusade, the rise of Castile, the perennial conflict with the Muslim-dominated kingdoms of al-Andalus, and even an eventual Christian reconquest. Some of the kingdoms ta'ifa with which the Leonese would relate were extensive kingdoms with strong commercial economies as well as a well-sophisticated intellectual life. Fernando I and Queen Sancha were in no way dominant in relation to the kingdoms ta'ifa, and they did not focus on the so-called "reconquest", but on the consolidation of royal authority in León and Galicia-Portugal, while from time to time they defended external challenges on their Castilian borders, also in the kingdom of Navarre.

The kings of Leon were not concerned with religious warfare against their Muslim neighbors, although they sometimes found themselves in conflict with them, just as they did with the other neighboring Christian kingdoms. Instead, Fernando and Sancha concentrated on rebuilding and consolidating their diffuse, fragile and insecure kingdoms in the northwest, and especially on the Galician-Portuguese border. This would culminate with the conquest of Coimbra in the year 1064. In the later Christian narrative sources, which begin with The Silent History, the struggle for Coimbra is represented as a direct dispute between Muslims and Christians. But this was not a crusade, guided by religious principle. In the battle for Coimbra, there were probably Mozarabs fighting on both sides. In the middle of the eleventh century, religious relations were less binary and more fluid than they became later; this was a culture in which the crossing of borders—in the sense of transfers of allegiance between Muslim and Christian rulers—was a constant.