They rose to prominence in the 10th century as counts in Saldaña, Carrión and Liébana, and reached their apogee when, allied with Córdoba warlord, Almanzor, their head, García Gómez, expelled king Vermudo II of León and briefly ruled there.
On his death, the senior line of the family was eclipsed, but a younger branch would return to prominence, producing Pedro Ansúrez, one of the premier noblemen under king Alfonso VI and queen Urraca in the late 11th and early 12th centuries.
Diego's patronymic, indicating his father's name was Munio, along with the family's holding of lands around Liébana led Castilian historian Justo Pérez de Urbel to suggest that his parents were the Munio Diaz and wife Gulatrudia, who appear in the documentation of San Martin de Liébana (later Santo Toribio) from the year 914.
[4] Following a 920 campaign of Abd-ar-Rahman III against León, king Ordoño II launched a punitive expedition targeting the Castilian counts in the lands around Carrión who had not turned up to fight.
Though not explicitly named, the Banu Gómez leader would have been Diego Muñoz, joining the Count of Castile, Fernando Ansúrez in a raid into the Leonese plains, where they defeated the king's army, but the rebellion came to naught, as Ramiro was able to capture and blind Alfonso and other rivals.
Through the daughter Elvira, who married count Fernando Bermúdez of Cea, they would be grandparents of queen Jimena Fernández, wife of García Sánchez II of Pamplona.
He likely fought in the disastrous Battle of San Esteban de Gormaz, where a coalition of Christian forces organized by Elvira was soundly defeated, a loss that led the Galician nobility to elevate a competitor for the throne, Ramiro's cousin Bermudo Ordóñez.
As such, Gómez found himself excluded from court when in 985 the Galician candidate proved successful, supplanting Ramiro and taking the crown of León as Bermudo II.
The year after his father's death, García initiated the first of his rebellions, calling himself elaborately proconsul dux eninentor in a 988 document, before being suppressed in early 989.
García would govern the eastern part of the kingdom, including the eponymous capitol, on Córdoba's behalf, referring to himself as 'ruling in León' in 990 (imperantem Garceani Gomiz in Legione).
[14] In 991, the king divorced his Galician wife, Velasquita, in favor of a new marriage to the daughter of the Count of Castile, García Fernández, leading to a new rebellion headed by her kin.
Her sister was wife of Gonzalo Vermúdez and mother-in-law of García, and these two, along with count Pelayo Rodríguez and a junior member of the Banu Gómez, Munio Fernández would again force Bermudo to abandon León by 992, but the next year he again was able to return and suppress the rebellion.
In 1005, García would incorporate Cea and Grajal into his territories, and amidst conflict with the Leonese king's guardian, count Menendo González, would claim the title 'count of León', implying another rebellion.
Count Fáfila Fernández was father of two known children, a daughter, Elvira, married to the last of the senior line of the family, Munio Gómez, and a poorly-documented son, Ordoño Fáfilaz.
Following the death of Sancho III of Pamplona, he appears at court and is given the rank of count, but he died not long thereafter, in 1038, leaving children who were all dead without issue by 1060.
[27] The youngest son of Diego Fernández, Gómez Díaz, likewise appears as count in 1042, and succeeded in reacquiring most of the dispersed lands once held by the senior line of the family, receiving Liébana and Carrión following the death of his brother Fernando, and wresting Saldaña from the family of Alfonso Díaz, to whom it had passed with the extinction of the senior line of Banu Gómez.
His status was further amplified by his marriage to Teresa Peláez, daughter of count Pelayo Fróilaz and Aldonza Ordóñez, a granddaughter of both of the rival kings, Ramiro III and Bermudo II.
[37] His half-brother, count Diego Ansúrez, inherited from his mother lands in Asturias, and would be active in the Astorga region in the 1070s, before dying in the early 1080s (perhaps 1081), leaving by his wife Tezguenza Rodríguez a sole daughter, Elvira.
A younger son of count Fernando Díaz, he was a prominent landholder on the Tierra de Campos, due not only to lands that came from his mother, Mansuara Fáfilaz, but also having inherited from his brother Osorio when the latter died.
In alliance with Córdoba, the rebels briefly forced the king to abandon the capitol, but on his recovery of the kingdom, Bermudo deprived Munio and his co-conspirators of many of their lands.
[51] He seems to have been rehabilitated by 997, when he appears as count and was exercising judicial authority in the region of Astorga, he also had acquired rights in Cimanes de la Vega.
[57] Other children of Munio Fernández were daughters Teresa, successively wife of Godesteo Díaz and Pedro Fróilaz, count of Bierzo, and María, as well as an additional son, Juan Muñiz.
He married an heiress of the Banu Mirel clan, and his family became major landholders in the region over the next several generations, until each of the branches ended in the male line.
The tale of Bernardo del Carpio first appears in the 13th century, and relates the saga of the son of a legendary Sancho Díaz, count of Saldaña.
Their son, Bernardo is raised by Alfonso as heir, but his attempts to get the king to release his father come to naught, and he eventually turns to rebellion and revenge.
[65] The epic appears to combine two distinct narratives, an Old French tale related to The Song of Roland (a variant related then dismissed by one of the earliest surviving versions instead makes Bernardo a nephew of Charlemagne, like the Roland of The Song) that would be merged with a native Iberian story involving the rebellion of the counts of Saldaña, while also drawing from the 13th century internecine disputes between the Kingdoms of León and Castile.
Pick points to several parallels, geographic and thematic, between this legendary tale of a count of Saldaña and the historical fractious relationship between the senior line of the Banu Gómez and the Leonese kings.
[66] The second legendary representation of the Banu Gómez builds on the historical antagonism between Rodrigo Díaz de Vivar, El Cid, and the family of count Pedro Ansúrez.
The brothers respond to the humiliating failure of their plot to assassinate one of El Cid's allies by binding and beating their wives, and abandoning them in a forest to be eaten by wolves.
The infantes are best viewed as literary constructs, composite characters intended to embody the rivalry and antagonism between El Cid and the Banu Gómez.