Hippolus is an ancient Greek mariner credited in Pliny the Elder's Periplus of the Erythyaean Sea with the discovery in 45 AD of the pattern of monsoon winds.[1] These winds enabled ships to leave Ocelis near Aden in the spring and arrive at the west coast of south India[2] in forty days. Then in the autumn the pattern of winds reversed allowing an equally speedy return from India. This resulted in a dramatic increase in trade between the Indian and the Greco-Roman world. This golden age of east-west sea trade lasted until Islamic expansion captured the ports in Egypt and the Ottoman empire.