Ptolemy III Euergetes
When not expounding his cosmology, Cosmas proves to be an interesting and reliable guide, providing a window into a world that has since disappeared. He happened to be in Ethiopia when the King of Axum was preparing a 522 or 525 AD military expedition to attack Jewish Arabs in Yemen. He recorded now-vanished inscriptions such as the Monumentum Adulitanum (which he mistakenly attributed to Ptolemy III Euergetes).