Legends of Terra Australis Incognita—an "unknown land of the South"—date back to Roman times and before, and were commonplace in medieval geography, although not based on any documented knowledge of the continent. Ptolemy's maps, which became well known in Europe during the Renaissance, did not actually depict such a continent, but they did show an Africa which had no southern oceanic boundary (and which therefore might extend all the way to the South Pole), and also raised the possibility that the Indian Ocean was entirely enclosed by land. Christian thinkers did not discount the idea that there might be land beyond the southern seas, but the issue of whether it could be inhabited was controversial.