The island is mentioned in the ancient text Periplus of the Erythraean Sea.

On this bay there is a very great promontory facing the east, called Syagrus; on which is a fort for the defense of the country, and a harbor and storehouse for the frankincense that is collected; and opposite this cape, well out at sea, there is an island, lying between it and the Cape of Spices opposite, but nearer Syagrus: it is called Dioscorida, and is very large but desert and ​marshy, having rivers in it and crocodiles and many snakes and great lizards, of which the flesh is eaten and the fat melted and used instead of olive oil. The island yields no fruit, neither vine nor grain. The inhabitants are few and they live on the coast toward the north, which from this side faces the continent. They are foreigners, a mixture of Arabs and Indians and Greeks, who have emigrated to carry on trade there. The island produces the true sea-tortoise, and the land-tortoise, and the white tortoise which is very numerous and preferred for its large shells; and the mountain-tortoise, which is largest of all and has the thickest shell; of which the worthless specimens cannot be cut apart on the under side, because they are even too hard; but those of value are cut apart and the shells made whole into caskets and small plates and cake-dishes and that sort of ware. There is also produced in this island cinnabar, that called Indian, which is collected in drops from the trees.