 Complete the following phrase:  The Caliphate of Córdoba was subsumed in a period of upheaval and civil war the Fitna of al-Andalus and collapsed in the early 11th century, spawning a series of ephemeral statelets, the taifas. Until the mid 11th century, most of the territorial expansion southwards of the Kingdom of AsturiasLeón was carried out through a policy of agricultural colonization rather than through military operations; then, profiting from the feebleness of the taifa principalities, Ferdid I of León seized Lamego and Viseu 10571058 and Coimbra 1064 away from the Taifa of Badajoz at times at war with the Taifa of Seville; Meanwhile, in the same year Coimbra was conquered, in the Northeastern part of the Iberian Peninsula, the Kingdom of Aragon 