For some centuries before the appearance of Islam the central factor in the politics of what we now call the “Near East ” was the constant warfare between the empires of Persia and Byzantium, and this, to a large extent, was fought out in Arabia. The products of India and further Asia as well as those of Arabia itself had become necessary to Byzantium and thus Persia was able to bring economic pressure to bear, and to do this more effectually, endeavoured to secure a strong hold on Arabia, and especially on South Arabia, which was the weakest point in the economic barrier designed to cut off Oriental products from the Byzantine markets.