The Red Sea, one of the main trade routes in Antiquity, was explored by Egyptians and Phoenicians during the last two millennia BCE. In the 6th century, BCE Greek explorer Scylax of Caryanda made a journey to India, working for the Persian king Darius, and his now-lost account put the Indian Ocean on the maps of Greek geographers. The Greeks began to explore the Indian Ocean following the conquests of Alexander the Great, who ordered a circumnavigation of the Arabian Peninsula in 323 BCE. During the two centuries that followed the reports of the explorers of Ptolemaic Egypt resulted in the best maps of the region until the Portuguese era many centuries later. The main interest in the region for the Ptolemies was not commercial but military; they explored Africa to hunt for war elephants.