There were obvious geographical and historical reasons why the kingdom of Portugal should furnish the important series of incidents in the expansion of geographical knowledge which now claims attention. The Arab power in the Iberian peninsula had been broken, and the Portuguese monarchy had established itself during the twelfth century. The Arab mantle of the explorer descended upon Portuguese shoulders. The small kingdom has a large extent of coastline; and not only is communication with Europe by land through the passes at either end of the Pyrenees comparatively difficult, but between those passes and Portugal were Spanish states, with which Portuguese relations were by no means amicable. Thus there was little opportunity for the commercial expansion of Portugal except over-seas. The first important figure in the history of this expansion is that of Prince Henry, surnamed the Navigator (1394–1460), fifth son of King John I. His objects were to extend Portuguese commercial interests mainly in West Africa, and also, it would appear, to discover new lands, if they were to be discovered, to the west of those Atlantic islands which formed the limit of knowledge to the west from very early times. Even the knowledge of the islands themselves was indefinite enough; so that when, in or about 1415, Henry began sending his seamen to the Canaries and later to the Madeira and the Azores, he was inspiring, if not actual discovery, at any rate the acquisition of largely new information. Between 1415 and 1431 colonization and trade had already begun to be established in some of the islands; and, though the Portuguese navigators did not forestall Columbus, it is likely that they conceived the possibility of a westward route to the Far East. Prince Henry’s residence from 1438 to 1460 was Sagres, which consequently became a centre for geographical research, for he gathered about him expert cartographers and instructors for his navigators, whom he supplied with the best obtainable instruments, maps, and information: he used not only European but also Arab sources. With regard to the West African coast, he experienced some years of comparative failure; but from 1444 explorations here were rapidly extended, and a few of the leading navigators and explorers who worked under Prince Henry’s direction and after his death may be mentioned. In 1443 John Fernandez travelled inland in the district of Rio de Oro, and collected valuable information about the resources, physical conditions, and people of the south-west part of the Sahara. He made further journeys in 1446–47. Diogo Gomez, in 1448, made his way up the Gambia river. Alvise Cadamosto, a Venetian in Prince Henry’s service, was working in 1455 south of the Senegal; and in 1456 he visited, and probably actually discovered, the Cape Verde Islands. His accounts of his voyages were full and valuable, and he also dealt with the explorations of Pedro de Cintra, in 1461 or 1462, to Sierra Leone and the Gold Coast.