 Complete the following phrase:  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 ByzantinePersian conflict opened the way for Islam. The Sasanian Empire rapidly succumbed to these attacks and was completely destroyed. During the ByzantineArab Wars, the exhausted Byzantine Empires recently regained eastern and southern provinces of Syria, 