At the period Pliny wrote his Natural History, the whole coast of Arabia appears to have become tolerably well known to the Greeks and Romans. With the western and southern portions of the peninsula they had perhaps long been acquainted; but their knowledge of the eastern and more remote parts was of much more recent date. Regarding the history of their gradual acquisition of this knowledge, the light afforded us is very faint. Arrian mentions that the first attempt to sail round the Arabian Chersonese was made from the Red Sea in the hope of reaching the Persian and Susian shores, but that the expedition, after having coasted along the greatest part of Arabia, was compelled by want of water to sail back again. Who these navigators were, and by whose command they undertook the journey, he does not say, but it seems probable they came from Egypt.