From the 7th century onwards, as the Byzantines and neighbouring Sasanid Persians were severely weakened due to the protracted, centuries-lasting and frequent Byzantine–Sasanian wars, the Muslim Arabs began to make inroads into historically Roman territory, taking the Levant and North Africa and making inroads into Asia Minor. In the mid 7th century CE, following the Muslim conquest of Persia, Islam penetrated into the Caucasus region. Over the next centuries Muslim forces took Cyprus, Malta, Crete, Sicily and parts of southern Italy. Between 711 and 720, most of the lands of the Visigothic Kingdom of Iberia was brought under Muslim rule — save for small areas in the northwest (Asturias) and largely Basque regions in the Pyrenees. This territory, under the Arabic name Al-Andalus, became part of the expanding Umayyad Caliphate. The unsuccessful second siege of Constantinople (717) weakened the Umayyad dynasty and reduced their prestige. The Umayyads were then defeated by the Frankish leader Charles Martel at the Battle of Poitiers in 732, which ended their northward advance. In the remote regions of north-western Iberia and the middle Pyrenees the power of the Muslims in the south was scarcely felt. It was here that the foundations of the Christian kingdoms of Asturias, Leon and Galicia were laid and from where the reconquest of the Iberian Peninsula would start. However, no coordinated attempt would be made to drive the Moors out. The Christian kingdoms were mainly focussed on their own internal power struggles. As a result, the Reconquista took the greater part of eight hundred years, in which period a long list of Alfonsos, Sanchos, Ordoños, Ramiros, Fernandos and Bermudos would be fighting their Christian rivals as much as the Muslim invaders.