Recent historiography has managed to provide scholars with a better understanding of the factors and conditions which facilitated the rise of the Banū-l Aḥmar in southern Iberia. Most scholars agree that the Battle of Las Navas de Tolosa (1212) and the death of the Almohad Caliph Abū Ya‘qūb Yūsuf II (r. 1213–1224) in 1224 left a power vacuum in southern Iberia which resulted in a struggle between various local Andalusī factions. For much of the 1220s and 1230s, therefore, al-Andalus was plagued by internal conflict in addition to being subject to the continuing raids and conquests of Fernando III, king of Castile and León, and Jaime I of Aragón. Among the many local strongmen to emerge in the ensuing power struggle was Muḥammad ibn Yūsuf ibn al-Aḥmar, who became ruler of the frontier town of Arjona, slightly north of Jaén, in 1232 following his rebellion against Ibn Hūd, an Andalusī warlord who had managed to impose his authority in a significant portion of al-Andalus in the late 1220s. From his base in Arjona, Ibn al-Aḥmar gradually expanded his influence and control, adding Jaén (1233), Porcuna (1233), Baza (1233), Guadix (1233), Seville (1235), Granada (1238), Almería (1238), and Málaga (1238) to his dominions by 1238. Although Ibn al-Aḥmar had been briefly recognized as sovereign in Córdoba, the prestigious former seat of the Umayyad Caliphate, in 1233, the capture of the city by his ally Fernando III in 1236 ended any Naṣrid pretensions or claims to the city.
Perhaps the most significant of all the political agreements which Ibn al-Aḥmar entered into during the course of his long career was that with Fernando III, as it laid the geographical and political basis of the Naṣrid kingdom. Shortly after the Castilian conquest of Córdoba, cross-border raids and skirmishes occurred between forces loyal to Ibn al-Aḥmar and those loyal to Fernando III, eventually culminating in major warfare. When Arjona was captured by Fernando III in 1244 and Jaén was besieged in 1245, Ibn al-Aḥmar decided to surrender Jaén in exchange for a twenty-year truce and a tribute of 150,000 maravedís to Castile. This agreement, concluded in 1246, which some scholars have termed “the birth certificate of the Naṣrid kingdom,” along with the subsequent fall of Seville in 1248, allowed Ibn al-Aḥmar to consolidate his authority in what remained of al-Andalus. Perhaps the most controversial and humiliating condition, from the perspective of contemporary Muslims, of this treaty was that Ibn al-Aḥmar was forced to render military assistance to Castile, thereby aiding Fernando’s conquests; this was particularly notable in the siege of Seville where 500 Granadan knights took part.
(Later representation of Ibn al-Ahmar pledging allegiance to Ferdinand III. Capilla de Santa Catalina, Burgos Cathedral)
Moreover, Muḥammad ibn al-Aḥmar was forced to look on while Alfonso X, who succeeded Fernando III in 1252, conquered the cities of Cádiz, Niebla, and Jerez. In doing so, Ibn al-Aḥmar directly played a role in the dismantling of Islamic political (and, thus, religious) authority in a significant portion of southern Iberia in exchange for establishing his sovereignty, as a vassal of Castile, in Granada and its neighboring districts.
Many historians have emphasized that the rise to power of Ibn al-Aḥmar cannot be understood without considering the broader context of power politics in al-Andalus during the 1230s. At various stages in his rise to power, between his emergence as lord of Arjona in 1232 and the definitive establishment of the kingdom of Granada in 1247, Ibn al-Aḥmar entered into a series of political arrangements with various powers, theoretically pledging himself in vassalage to the Almohads, the Ḥafṣids, and Fernando III, while simultaneously pursuing an independent policy. Although Castilian sources (and the Spanish historiography which relies upon these sources) strongly emphasize the submission of Muḥammad ibn al-Aḥmar to Fernando III as reflecting the vassal status of the former to the latter, some historians have been skeptical of the political reality underlying this assertion. For Leonard Patrick Harvey, the language of vassalage which derives from the Castilian sources is not the most helpful conceptual framework to understand the emergence of Ibn al-Aḥmar because it does not allow historians to “appreciate the peculiarly delicate form of equilibrium on the frontier between two civilizations which the Naṣrids were striving to maintain.” Although there is merit to this argument, it is nevertheless important to keep in mind that the balance was clearly in Castile’s favor, as is evident from Ibn al-Aḥmar’s surrender of territory and payment of tribute; in other words, this was not an alliance or truce between political equals. However one wishes to classify this arrangement, it is clear that the situation which prevailed between 1246 and 1264, in which there was relative stability (and even peace) between Naṣrid Granada and Christian Spain, was short-lived.
The year 1264 marks a major turning point in the relationship between Muḥammad and Alfonso X. It was during this year that Ibn al-Aḥmar openly allied himself with the Marīnid dynasty in Fez, who had succeeded the Almohads. Shortly afterwards, the first major contingents of Marīnid ghāzīs (holy warriors) crossed into Spain in order to participate in jihād and, specifically, to assist the Mudéjar revolt which had erupted in Castile. The question of whether or not the Mudéjar revolt was directly instigated by Muḥammad I has been debated in previous scholarship; however, it is clear that the uprising was encouraged and facilitated by Granada once it had begun. In fact, the Mudéjar rebels in the towns of Jerez, Utrera, Lebrija, and Murcia recognized Muḥammad ibn al-Aḥmar as their sovereign in the course of the uprising. This led to the renewal of hostilities between Muḥammad I and Alfonso X in 1265 and the invasion of Murcia by Jaime I of Aragón, who finally suppressed the revolt in 1266. By 1267, a truce was concluded between Granada and Castile on the basis of Muḥammad’s renunciation of all territorial claims to Jerez and Murcia, in addition to his agreeing to pay an increased tribute of 250,000 maravedís. Although this seems to represent a return to the pre-1264 reality, the episode of the Mudéjar uprising in 1264–1266 demonstrates that far from simply existing in a state of vassalage, the relationship of the kingdom of Granada vis-à-vis Castile was far more complicated. Despite the restoration of the status quo, in which the kingdom of Granada was once again forced to surrender territory and pay tribute to Castile in exchange for a truce, Muḥammad I had by the end of his reign become disillusioned with the political reality in Iberia. In fact, he explicitly encouraged his successor, Muḥammad II, to increasingly rely on the Banū Marīn from North Africa in order to shift the balance with the Christian kingdoms.
This new element, the Marīnids, which was introduced into the political equation in southern Iberia, had a major impact on the power dynamic in al-Andalus over the next several decades, and remained a significant political force until the late fourteenth century. For the next seventy-five years, the power politics of southern Iberia was dominated by the ever-changing network of alliances between Naṣrid kingdom of Granada, the Marīnids, and the Crown of Castile-León. It was this political situation, in which the Naṣrids balanced the Banū Marīn and Christian kingdoms against one another which prolonged the existence of Granada while allowing it to preserve its independence during much of the fourteenth century.
 For the most comprehensive survey on the rise of the Naṣrids, see Bárbara Boloix Gallardo, De la Taifa de Arjona al Reino Nazarí de Granada, 1232–1246 (Jaén: Instituto de Estudios Giennenses, 2005). The best narrative summary in English is that provided by L.P. Harvey, Islamic Spain, 1250 to 1500 (Chicago: Chicago University Press, 1990), pp. 20–40. For a good general introduction to the chronology of the Naṣrids, see J.D. Latham and Antonio Fernández-Puertas, “Naṣrids, Ar. Banū Naṣr,” Encyclopedia of Islam, Second Edition (Brill: Brill Online, 2011), ed. Paul Bearman et al.
 Rachel Arié, El Reino Nasrí de Granada (Madrid: Editorial MAPFRE), pp. 17–19; Miguel Ángel Ladero Quesada, Granada. Historia de un País Islámico (Madrid: Editorial Gredos, 1989), p. 125; Hugh Kennedy, Muslim Spain and Portugal: A Political History of al-Andalus (London: Longman, 1996), pp. 226–228; Robert I. Burns, Islam under the Crusaders: Colonial Survival in the Thirteenth-Century Kingdom of Valencia (Princeton: Princeton University Press, 1973), pp. 28–31; Ibn Khaldūn, Tārīkh, 6: 311, 7: 197
 Kennedy, Muslim Spain and Portugal, pp. 268–272; Chejne, Muslim Spain, pp. 97–98. For a detailed discussion of this period, see Gallardo, De la Taifa de Arjona al Reino Nazarí, pp. 17–37
 Aḥmad ibn Muḥammad ibn ‘Idhārī, al-Bayān al-Mughrib fī Akhbār al-Andalus wa al-Maghrib ( Beirut: Dār Kutub al-‘Ilmīyyah, 2009), 4: 371; Ibn Khaldūn, Tārīkh, 6: 313, 7: 197; Quesada, Granada, p. 125; Kennedy, Muslim Spain and Portugal, p. 274; Burns, Islam under the Crusaders, p. 31; Arié, El Reino Nasrí de Granada, pp. 19–20; Gallardo, De la Taifa de Arjona al Reino Nazarí, p. 60–63; Chejne, Muslim Spain, p. 98. Muḥammad ibn al-Aḥmar had previously sworn fealty to Ibn Hūd, a descendant of the taifa kings of Zaragoza who had been invested with power from the ‘Abbāsid Caliph. He lost much of his following and prestige following his defeat to a Christian army at the Battle of Alanje (1231), which led to the fall of Badajoz and the rest of Extremadura
 Ibn ‘Idhārī, al-Bayān al-Mughrib, 4: 418–419, 434; Ibn Khaldūn, Tārīkh, 6: 313; Quesada, Granada, p. 126; Kennedy, Muslim Spain and Portugal, p. 275; Arié, El Reino Nasrí de Granada, p. 20; Gallardo, De la Taifa de Arjona al Reino Nazarí, pp. 63–77
 Ibn ‘Idhārī, al-Bayān al-Mughrib, 4: 407–408; Joseph F. O’Callaghan, Reconquest and Crusade in Medieval Spain (Philadelphia: University of Pennsylvania Press, 2003), p. 95; Peter Linehan, Spain, 1157–1300: A Partible Inheritance (Oxford: Blackwell Publishing, 2011), p. 71; Ana Rodríguez López, La Consolidación Territorial de la Monarquía Feudal Castellana: Expansión y Fronteras durante el Reinado de Fernando III (Madrid: Consejo Superior de Investigaciones Científicas, 1994), p. 267; Arié, El Reino Nasrí de Granada, p. 20; Harvey, Islamic Spain, p. 22; Chejne, Muslim Spain, p. 98
 Kennedy, Muslim Spain and Portugal, p. 276; Gallardo, De la Taifa de Arjona al Reino Nazarí, p. 55; Chejne, Muslim Spain, p. 98
 Harvey, Islamic Spain, p. 23
 Ibn ‘Idhārī, al-Bayān al-Mughrib, 4: 444; López, La Consolidación Territorial, p. 129, 267; Quesada, Granada, p. 127; Kennedy, Muslim Spain and Portugal, p. 276; O’Callaghan, Reconquest and Crusade in Medieval Spain, pp. 110–111; Arié, El Reino Nasrí de Granada, p. 21; Gallardo, De la Taifa de Arjona al Reino Nazarí, pp. 77–83; Harvey, Islamic Spain, pp. 23–25
 López, La Consolidación Territorial, p. 129; Kennedy, Muslim Spain and Portugal, p. 276; O’Callaghan, Reconquest and Crusade in Medieval Spain, pp. 112–117 Gallardo, De la Taifa de Arjona al Reino Nazarí, p. 79; Ibn Khaldūn, Tārīkh, 7: 198. Since revisiting the historiographical debate is not the concern of this short overview, it suffices to underscore that the 1246 treaty was mutually beneficial to both parties; Muḥammad benefited from the opportunity to consolidate himself as the sole, legitimate sovereign authority in al-Andalus while Castile benefited from the massive tribute paid by the king of Granada
 Quesada, Granada, p. 127; López, La Consolidación Territorial, p. 268; Arié, El Reino Nasrí de Granada, pp. 22–23; Kennedy, Muslim Spain and Portugal, p. 272; Chejne, Muslim Spain, p. 271; Ibn Khaldūn, Tārīkh, 6: 312. Seville had revolted against Ibn al-Aḥmar in 1236 and reverted to the allegiance of Ibn Hūd, and, after the latter’s death, to the Almohad Caliph (Ibn Khaldūn, Tārīkh, 6: 312–313)
 During the reign of Muḥammad I, the kingdom of Granada extended from Algeciras and Gibraltar in the south, to the region just south of Murcia in the east, and the limits of the kingdom reached just south of the cities of Jaén and Cordoba. The kingdom consisted of several important cities, such as Ronda, Málaga, Guadix, and Almería, rich agricultural areas and was protected from attack by several natural frontiers, notably mountainous regions
 Jamil M. Abun Nasr, A History of the Maghrib in the Islamic Period (Cambridge: Cambridge University Press, 1987), p. 119; Kennedy, Muslim Spain and Portugal, p. 276; Arié, El Reino Nasrí de Granada, p. 23; Quesada, Granada, p. 12; Ibn ‘Idhārī, al-Bayān al-Mughrib, 4: 434; Ibn Khaldūn, Tārīkh, 6: 311, 313–314
 Primera Crónica General de España (Madrid: Editorial Gredos, 1955), ed. Ramón Menéndez Pidal, 2: 746; Harvey, Islamic Spain, p. 27
 Harvey, Islamic Spain, p. 28
 Kennedy, Muslim Spain and Portugal, p. 276
 Jaime I of Aragón, The Books of Deeds of James I of Aragon: A Translation of the Medieval Catalan Llibre del Fets (Burlington, VT: Ashgate, 2003), ed. and trans. Damian J. Smith and Helen Buffery, p. 283; Joseph O’Callaghan, The Gibraltar Crusade: Castile and the Battle for the Strait (Philadelphia: University of Pennsylvania Press, 2011), p. 36; Arié, El Reino Nasrí de Granada, p. 23; Quesada, Granada, pp. 130–131; Ibn ‘Idhārī, al-Bayān al-Mughrib, 4: 501, 503
 O’Callaghan, The Gibraltar Crusade, pp. 34–37; Kennedy, Muslim Spain and Portugal, p. 278; Harvey, Islamic Spain, pp. 52–54. Jaime I of Aragón, The Books of Deeds, p. 284 asserts that Ibn al-Aḥmar coordinated the uprising with the Mudéjars in Castile
 Ibn ‘Idhārī, al-Bayān al-Mughrib, 4: 502; Arié, El Reino Nasrí de Granada, pp. 23–24; O’Callaghan, The Gibraltar Crusade, p. 37; Kennedy, Muslim Spain and Portugal, p. 279; Harvey, Islamic Spain, pp. 52–54. This perspective is corroborated by Jaime’s narration of events in his Book of Deeds.
 Jaime I, Book of Deeds, pp. 284–327; Arié, El Reino Nasrí de Granada, p. 24. The failure of the Mudéjar uprising had massive consequences for the Muslims living under Castilian rule in Andalusia, with mass expulsions occurring in most of the areas affected by the rebellion and the subsequent repopulation of entire regions with Christian settlers
 Arié, El Reino Nasrí de Granada, p. 23; Kennedy, Muslim Spain and Portugal, p. 279; Quesada, Granada, p. 131. For a detailed discussion of the Mudéjar uprising, the role of Granada, and the impact on Castilian-Naṣrid relations, see O’Callaghan, Gibraltar Crusade, pp. 34–59
 Burns, Islam under the Crusaders, p. 41
 Al-Mabrūk Ghanīyah al-Usta, Ḥarakat al-Jihād al-Mushtarak ‘ala mada qarn fi ẓill al-silāt bayn Banī al-Aḥmar bi-Gharnāṭah wa Banī Marīn bi-Fās, 674–777 A.H./1275–1375 A.D (Tripoli: Markaz Jihād al-Lībīyyīn lil Dirāsat al-Tārīkhīyyah, 1995), pp. 117–297; O’Callaghan, Gibraltar Crusade, pp. 60–217; Quesada, Granada, pp. 134–156
 Kennedy, Muslim Spain and Portugal, pp. 280–88; Ibn Khaldūn, Tārīkh, 7: 93, 206–219, 221–222, 224–226, 259–260, 271–273. For the most comprehensive study of the Marīnids in Iberia, see Miguel Ángel Manzano Rodríguez, La Intervención de los Benimerines en la Península Ibérica (Madrid: Consejo Superior de Investigaciones Científicas, 1992)