Traveler and geographer. He explored the region south of Egypt as far as Cape Guardafui and east probably as far as India (Indicopleustes = voyager to India). On retiring from his travels, he entered the monastery of Raithu on the Peninsula of Sinai. Here he wrote his , an account of his travels and investigations with a description of the universe as he imagined it, and with explanatory maps. The work is valuable as being the first effort of patristic geography.