Alfonso IV of León in the context of "Marches"

The Kingdom of León was an independent kingdom situated in the northwest region of the Iberian Peninsula. It was founded in 910 when the Christian princes of Asturias along the northern coast of the peninsula shifted their capital from Oviedo to the city of León. The kings of León fought civil wars, wars against neighbouring kingdoms and campaigns by both the Moors and the Vikings, all in order to protect their kingdom's changing fortunes.

García is the first of the kings described by the charters as reigning in León. It is generally assumed that the old Asturian kingdom was divided among the three sons of Alfonso III of Asturias: García (León), Ordoño (Galicia) and Fruela (Asturias), as all three participated in deposing their father. When García died in 914, León went to Ordoño, who now ruled both León and Galicia as Ordoño II. At Ordoño's death in 924, the throne went to his brother Fruela II (924–925), who died of leprosy a year later. Fruela's death in 925 was followed by a civil war, after which Alfonso, the eldest son of Ordoño II, emerged as the new king Alfonso IV, ruling from 925 to 932. After a further power struggle, Ramiro, the younger brother of Alfonso IV, became king in 932, having captured his brother Alfonso, as well as the three sons of Fruela II – Alfonso, Ordoño and Ramiro. Alfonso IV may have died soon after, but he left two infant sons, called Ordoño and Fruela. When Ramiro died in 951, he left two sons by two different wives. When the elder son Ordoño III, who ruled from 951 to 956, suddenly died aged little more than thirty, he was succeeded by his younger half-brother Sancho I "The Fat" (956–966), as Ordoño had failed to produce a legitimate heir.

Ramiro II (c. 900 – 1 January 951), son of Ordoño II and Elvira Menendez, was a King of León from 931 until his death. Initially titular king only of a lesser part of the kingdom, he gained the crown of León (and with it, Galicia) after supplanting his brother Alfonso IV and cousin Alfonso Fróilaz in 931. The scant Anales castellanos primeros are a primary source for his reign.

He actively campaigned against the Moors, who referred to him as the Devil due to his ferocity and fervor in battle. He defeated the hosts of the Umayyad caliph, Abd al-Rahman III, at the Battle of Simancas (939).

Alfonso Fróilaz, called the Hunchback (Spanish el Jorobado), was briefly the king of the unified kingdom of Asturias, Galicia and León in 925. He succeeded his father, King Fruela II, in July 925 but was driven from the throne within the year by his cousins Sancho, Alfonso IV and Ramiro II, the sons of his uncle, Ordoño II. He was restored to a royal position in part of the kingdom after Alfonso IV took power in 926, but was violently deposed and forced into a monastery in 932.

Alfonso was the eldest son of Fruela II and had at least two younger brothers, Ordoño and Ramiro. Alfonso's short reign is poorly known. He is mentioned in the king list Names of the Catholic Kings of León, which appears in some manuscripts alongside the Chronicle of Albelda. A cryptic statement by the Asturian historian Sampiro that he "seemed to control the sceptre of his father" is the only other piece of evidence that he succeeded to the whole kingdom after his father.

Ordoño IV, called the Wicked or the Bad (c. 926–Córdoba, c. 962 or 963) was the king of León from 958 until 960, interrupting the reign of Sancho the Fat for a two-year period.

He was the son of Alfonso IV of León and his queen, Onneca Sánchez of Pamplona, and nephew of Ramiro II of León and of García Sánchez I of Pamplona.