Battle of Río Salado in the context of Afonso IV of Portugal

The Marinid dynasty (Arabic: المرينيون al-marīniyyūn) was a Berber Muslim dynasty that controlled present-day Morocco from the mid-13th to the 15th century and intermittently controlled other parts of North Africa (Algeria and Tunisia) and of the southern Iberian Peninsula (Spain) around Gibraltar. It was named after the Banu Marin (Arabic: بنو مرين, Berber: Ayt Mrin), a Zenata Berber tribe. It ruled the Marinid sultanate, founded by Abd al-Haqq I.

In 1244, after being at their service for several years, the Marinids overthrew the Almohads which had controlled Morocco. At the height of their power in the mid-14th century, during the reigns of Abu al-Hasan and his son Abu Inan, the Marinid dynasty briefly held sway over most of the Maghreb including large parts of modern-day Algeria and Tunisia. The Marinids supported the Emirate of Granada in al-Andalus in the 13th and 14th centuries and made an attempt to gain a direct foothold on the European side of the Strait of Gibraltar. They were however defeated at the Battle of Río Salado in 1340 and finished after the Castilians took Algeciras from the Marinids in 1344, definitively expelling them from the Iberian Peninsula. Starting in the early 15th century the Wattasid dynasty, a related ruling house, competed with the Marinid dynasty for control of the state and became de facto rulers between 1420 and 1459 while officially acting as regents or viziers. In 1465 the last Marinid sultan, Abd al-Haqq II, was finally overthrown and killed by a revolt in Fez, which led to the establishment of direct Wattasid rule over most of Morocco.

The Marinid dynasty (Arabic: المرينيون, romanized: al-Marīniyyūn) was a Sunni Muslim dynasty that controlled present-day Morocco from the mid-13th to the 15th century and intermittently controlled other parts of North Africa (Algeria and Tunisia) and of the southern Iberian Peninsula (Spain) around Gibraltar. They were a culturally Arabized dynasty of Berber origin. The dynasty takes its name from the Banu Marin (Arabic: بنو مرين; Berber languages: Ayt Mrin), the Zenata Berber tribe from which it originated.

After being at their service for a brief period, the Marinids waged war during the 13th century to overthrow the Almohads, who ruled the western Maghreb, eventually succeeding in 1269 with the capture of Marrakesh. At the height of their power in the mid-14th century, during the reigns of Abu al-Hasan and his son Abu Inan, the Marinid dynasty briefly held sway over most of the Maghreb including large parts of modern-day Algeria and Tunisia. They supported the Emirate of Granada in al-Andalus in the 13th and 14th centuries and made an attempt to gain a direct foothold on the European side of the Strait of Gibraltar. They were however defeated at the Battle of Río Salado in 1340 and finished after the Castilians took Algeciras in 1344, definitively expelling them from the Iberian Peninsula. Starting in the early 15th century, the Wattasid dynasty, a related ruling house, competed with the Marinid dynasty for control of the state and became de facto rulers between 1420 and 1459 while officially acting as regents or viziers. In 1465 the last Marinid sultan, Abd al-Haqq II, was finally overthrown and killed by a revolt in Fez, which led to the establishment of direct Wattasid rule over most of Morocco.

Alfonso XI (11 August 1311 – 26 March 1350), called the Avenger (el Justiciero), was King of Castile and León. He was the son of Ferdinand IV of Castile and his wife Constance of Portugal. Upon his father's death in 1312, several disputes ensued over who would hold regency, which were resolved in 1313.

Once Alfonso was declared an adult in 1325, he began a reign that would serve to strengthen royal power and became known for his victory in the Battle of Rio Salado. While leading a siege against Yusuf I of Granada, he died of the plague in Gibraltar.

Abu al-Hajjaj Yusuf ibn Ismail (29 June 1318 – 19 October 1354), known by the regnal name al-Muayyad billah (lit. 'He who is aided by God'), was the seventh Nasrid ruler of the Emirate of Granada on the Iberian Peninsula. The third son of Ismail I (r. 1314–1322), he was Sultan between 1333 and 1354, after his brother Muhammad IV (r. 1325–1333) was assassinated.

Coming to the throne at age fifteen, he was initially treated as a minor and given only limited power by his ministers and his grandmother Fatima. In February 1334, his representatives secured a four-year peace treaty with Granada's neighbours Castile and the Marinid Sultanate. Aragon joined in the treaty in May. After gaining more control of the government, in 1338 or 1340 he expelled the Banu Abi al-Ula family, who had masterminded the murder of his brother and had been the leaders of the Volunteers of the Faith—North African soldiers who fought for Granada. After the treaty expired, he allied himself with Abu al-Hasan Ali (r. 1331–1348) of the Marinids against Alfonso XI of Castile (r. 1312–1350). After winning a major naval victory in April 1340, the Marinid–Granadan alliance was decisively defeated on 30 October in the disastrous Battle of Río Salado. In its aftermath, Yusuf was unable to prevent Castile from taking several Granadan castles and towns, including Alcalá de Benzaide, Locubín, Priego and Benamejí. In 1342–1344, Alfonso XI besieged the strategic port of Algeciras. Yusuf led his troops in diversionary raids into Castilian territory, and later engaged the besieging army, but the city fell in March 1344. A ten-year peace treaty with Castile followed.