Neither empire was given much chance to recover, as within a few years they were struck by the onslaught of the Arabs, newly united by Islam, which Howard-Johnston likened to "a human tsunami". According to George Liska, the "unnecessarily prolonged Byzantine–Persian conflict opened the way for Islam". The Sasanian Empire rapidly succumbed to these attacks and was completely destroyed. During the Byzantine–Arab Wars, the exhausted Byzantine Empire's recently regained eastern and southern provinces of Syria, Armenia, Egypt, and North Africa were also lost, reducing the empire to a territorial core consisting of Anatolia and a scatter of islands and footholds in the Balkans and Italy. However, unlike Persia, the Byzantine Empire ultimately survived the Arab assault, holding onto its remaining territories and decisively repulsing two Arab sieges of its capital in 674–678 and 717–718. The Byzantine Empire also lost its territories in Crete and southern Italy to the Arabs in later conflicts, though these too were ultimately recovered. However, some losses were permanent, such as the loss of Spania, the remaining Byzantine holdings in Spain, which was conquered by the Visigoths by 629. Similarly, Corsica was taken by the Lombards in the 8th century. The Balearic Islands, Sardinia and Sicily were captured by Arabs in the 10th century.