The long sixteenth century saw the greatest single shift in European geographical knowledge and understanding that has occurred in written history. This book demonstrates how over this key period western Europeans moved from seeing the northern temperate regions of the world as the only knowable space to thinking of the world as a global unit in which God made all parts of the sphere for human exploitation and to interact with one another. In the fifth century BC the ancient Greeks had developed the idea that only parts of the world were inhabitable. This ‘inhabitable world’, termed oikoumene, in which boundaries of climate and Ocean separated the knowable regions of the earth from the rest of the sphere, became the primary model in geographical thought for more than two thousand years. The quotation above from Gomes Eanes de Zurara's Chronicle of Guinea written about 1450, at the very cusp of the period of European expansion, captures the fear with which the world beyond the oikoumene was viewed. According to Zurara, the mariners were certain that there was no point in venturing beyond Cape Bojador since neither sea nor land could support human life. Humans were confined to the oikoumene. In the late fifteenth and sixteenth centuries, however, the world came to be seen as a truly global space and the traditional boundaries of classical and medieval geographical thought were undermined. Nonetheless, ideas of inhabitability continued to dominate geographical literature throughout the sixteenth century.