After the Abbasid Revolution which overthrew the Umayyad Caliphate, Muslims of the Iberian Peninsula (called Al-Andalus by the Muslims) declared an independent emirate, with its capital in Córdoba in 756.[7] The Umayyad-ruled emirate received waves of refugees who escaped the revolution in the Middle East, and soon became a center of intellectual developments.[7] The 844 raid was the first confirmed large-scale Viking incursion on the peninsula.[7] During this period, Al-Andalus was in the state of uneasy peace with the Iberian and Frankish Christians to its north, dotted by constant skirmishes and occasional military campaigns across a sort of a demilitarized zone between them.[7] There might have been small Viking incursions to the Basque Country in early ninth century prior to the raid.[7]