In the first half of the 10th century, an intra-family succession squabble, rebellions and rivalries with competing families, in the face of vigorous monarchs to the north and south, led to the sequential loss of all of their land.

[2][a] According to the 10th century Muwallad historian, Ibn al-Qūṭiyya, Count Cassius converted to Islam in 714 as the mawlā (client) of the Umayyads, shortly after their conquest of Hispania.

Under the Banu Qasi, the region of Upper Ebro (modern districts of Logroño and southern Navarre, based in Tudela) formed a semi-autonomous principality.

In actuality, even more menacing was the gradual eastwards expansion of the Asturian Kingdom; while in the south lay the Caliphate of Córdoba, ever anxious to impose its authority over the frontier regions.

As a local Muslim dynasty in the Ebro valley (the Upper March of Al-Andalus; Arabic: الثغر الأعلى, Aṯ-Ṯaḡr al-Aʿlà), the Banu Qasi were nominally clients of the emirate, but they thrived on regional rivalries and alliances with other Muwallad dynasties of the Upper March, the Vascon tribal chieftains of Pamplona and Aragon,[4] as well as with the Catalan counts of Pallars-Ribagorza to the north[5] and Barcelona to the east, the Kingdom of Asturias to the west and the Umayyads to the south over the next two centuries.

The cultural ambivalence of the Banu Qasi is also demonstrated by their mixed use of names: for example, Arabic (Muhammad, Musa, Abd Allah), Latinate (Awriya, Furtun, Lubb), and Basque (Garshiya).

The Umayyads of Cordova sanctioned the rule of the Banu Qasi and repeatedly granted them autonomy by appointing them as governors, only to replace them as they expressed too much independence, or launch punitive military expeditions into the region.

Such acts on the part of the Umayyads demonstrated their failure to ever fully resolve the problem of effective, central control of outlying regions.

[12] "This is perhaps one of the most quoted paragraphs by historians who on the basis of this brief news, have woven a complex web of relationships involving the Banu Qasi, the Arista and the Carolingians".

Spanish historian Claudio Sánchez Albornoz did not agree with this interpretation and believed that it had been the people of Pamplona, without any outside intervention, who took matters in their own hands.

Historians agree that in the 840s, after the expulsion from his lands of a kinsman, 'Abd al-Jabbar al-Qasawi, Musa launched a series of revolts in conjunction with his maternal half-brother, Íñigo Arista of Pamplona.

The 851/2 deaths of Íñigo Arista and Abd ar-Rahman II, as well as a victory over Christian forces at Albelda, gave Musa unprecedented status.

In 859, Ordoño I of Asturias and García Íñiguez of Pamplona joined forces to deal Musa a crushing defeat at Albelda, which passed into Christian legend as the Battle of Clavijo.

Furtun ibn Musa occupied Tudela, whose governor the Banu Qasi imprisoned at Arnedo, then killed following an escape.

He first bought off the rebels of Toledo with governorships, and this encouraged Amrus to offer his loyalty, for which he was rewarded with Huesca where he captured Mutarrif and his family, including wife Belasquita, the daughter of García Íñiguez of Pamplona.

In spite of a desperate attack by the combined troops of his brothers, Mutarrif and three sons, Muhammad, Musa and Lubb, were taken to Córdoba and crucified.

This resulted in a consolidated Banu Qasi powerbase around Arnedo, Borja, Calahorra and Viguera, with Isma'il holding an enclave to the east, around Monzon and Lleida.

[33] In 891, Muhammad defeated a Christian force at Castro Sibiriano,[34] but he dedicated most of his efforts in his final years against Tujibid Zaragoza, initiating what would become a 17-year siege.

His head was presented to the Tujibids, who sent it to Córdoba, where it was displayed in front of the palace for eight days before being buried with the honors due a brave foe.

[38] Returning through Toledo in 898, he next marched to Jaén, with the intent of forming a coalition with another rebel, Umar ibn Hafsun, but before Umar reached Jaén, the news of his father's death at Zaragoza forced Lubb's return to Tudela, where he formally recognized the sovereignty of the emir, Abd Allah, in exchange for the formal governorship over Tudela and Tarazona.

[39] His return north found al-Tawil moving to take advantage of the temporary power vacuum and three weeks after his father's death, Lubb captured the Huesca ruler in a skirmish.

Perhaps in 900, Alfonso III, in conjunction with Fortún Garcés of Pamplona, launched a raid against Tarazona, in Lubb's realms; which he successfully blocked.

This threat neutralized, Lubb turned toward Pallars, ravaging the lands, killing hundreds and taking a thousand captives, including Isarn, Count Raymond's son, who was kept in Tudela for a decade before being freed.

[47] Al-Tawil defected and escaped, while Galindo was crushed and forced to recognize Sancho as feudal sovereign, ending the autonomy of the Aragon.

[47] In 914, Sancho turned the tables, marching into the heart of the Banu Qasi homeland, taking Arnedo and attacking Calahorra.

[52] Since the death of Lubb in 907, the Banu Qasi had been left fractured and weakened in the face of two resurgent powers: to the north and west, a collaboration between the new king of León, Ordoño II, and Sancho I of Navarre brought a strong army south, ravaging the Banu Qasi lands around Viguera, Najera and Tudela in 918, while the young and energetic Abd ar-Rahman III, who was to temporarily reverse the centrifugal forces at work in the Emirate, soon to be Caliphate of Córdoba, sent armies north, routing the Christians.

[54] In 920, the emir, Abd ar-Rahman III, personally led the Cordoban army north, and forced Sancho to abandon fortifications he had been building.

[55] In 923, the Christian allies brought another force south, and while Muhammad ibn Abd Allah formed a coalition of local nobles to resist it, their armies were dispersed and Viguera and Najera fell.

Their rivals the Tujibids would follow their model, making an independent peace with Leon in 937, a move that resulted in a punitive expedition from the Caliph similar to those of prior years against the Banu Qasi.

[61][62] Two other Taifa crowns were ruled by men with names reminiscent of the Banu Qasi and are claimed as dynastic members, although there is no evidence of any actual genealogical connection.