Brittany's active part in the maritime history of France is due not only to its ragged contour, its inshore and offshore islands, its forward location on the Atlantic which brought it near to the fisheries of Newfoundland and the trade of the West Indies, but also to the fact that the "Golden Belt," which, with but few interruptions, forms a band of fertility along the coast, has supported a denser population than the sterile granitic soils of the interior,[476] while the sea near by varied and enriched the diet of the inhabitants by its abundance of fish, and in its limy seaweed yielded a valuable fertilizer for their gardens.[477] The small but countless alluvial deposits at the fiord heads in Norway, aided by the products of the sea, are able to support a considerable number of people. Hence the narrow coastal rim of that country shows always a density of population double or quadruple that of the next density belt toward the mountainous interior, and contains seventeen out of Norway's nineteen towns having more than 5,000 inhabitants.[478] It is this relative fertility of the coastal regions, as opposed to the sterile interior, that has brought so large a part of Norway's people in contact with the Atlantic and helped give them a prominent place in maritime history. [Sidenote: Barren coast of fertile hinterland.] Occasionally an infertile and sparsely inhabited littoral bordering a limited zone of singular productivity, especially if favorably located for international trade, will develop marked maritime activity, both in trade and commercial colonization. Such was Arabian Yemen, the home of the ancient Sabaeans on the Red Sea, stretching from the Straits of Bab-el-Mandeb north-westward for 500 miles. Here a mountain range, rising to 10,000 feet and bordering the plateau desert of central Arabia, condenses the vapors of the summer monsoon and creates a long-drawn oasis, where terraced coffee gardens and orchards blossom in the irrigated soil; but the arid coastal strip at its feet, harboring a sparse population only along its tricking streams, developed a series of considerable ports as outlets for the abundant products and crowded population of the highlands.[479] A location on the busy sea lane leading from the Indian Ocean to the Mediterranean, near the meeting place of three continents, made the merchants of the Yemen coast, like the Oman Arabs to the north, middlemen in the trade of Europe with eastern Africa and India.[480] Therefore, even in the second century these Sabaeans had their trading stations scattered along the east coast of Africa as far south as Zanzibar.[481] In 1502 Vasco da Gama found Arabs, either of Oman or Yemen, yet farther south in Sofala, the port for the ivory and gold trade. Some of them he employed as pilots to steer his course to India.[482]