The Arabian peninsula already played a role in the power struggles of the Byzantines and Sasanians. While Byzantium allied itself with the Kingdom of Aksum in the horn of Africa, the Sasanian Empire assisted the Himyarite Kingdom in what is now Yemen (southwest Arabia). Thus the clash between the kingdoms of Aksum and Himyar in 525 displayed a higher power struggle between Byzantium and Persia for control of the Red Sea trade. Territorial wars soon became common, with the Byzantines and Sasanians fighting over upper Mesopotamia and Armenia and key cities that facilitated trade from Arabia, India, and China. Byzantium, as the continuation of the Eastern Roman Empire, continued control of the latter's territories in the Middle East. Since 527, this included Anatolia, Syria, Lebanon, Palestine, and Egypt. But in 603 the Sasanians invaded, conquering Damascus and Egypt. It was Emperor Heraclius who was able to repel these invasions, and in 628 he replaced the Sasanian Great King with a more docile one. But the fighting weakened both states, leaving the stage open to a new power.