=116.= NORTHERN AFRICA alone was known to the ancients, and its features were well marked and peculiar. Close along the Mediterranean lay a narrow strip of fertile land, watered by short streams which descended from the Atlas range. These mountains formed a rocky and scantily inhabited region to the southward, though producing in certain portions abundance of dates. Next came the Great Desert, varied only by a few small and scattered oases, where springs of water nourished a rich vegetation. South of the Sahara was a fertile inland country, near whose large rivers and lakes were cities and a numerous population; but these central African states were only visited by an occasional caravan which crossed the desert from the north, and had no political connection with the rest of the world. =117.= In the western portion of Northern Africa, the mountains rise more gradually by a series of natural terraces from the sea, and the fertile country here attains a width of two hundred miles. This well watered, fruitful, and comparatively healthful region, is one of the most favored on the globe. In ancient times it was one vast corn-field from the Atlas to the Mediterranean. Here the native kingdom of Maurita´nia flourished; and after it was subdued by the Romans, the same fertile fields afforded bread to the rest of the civilized world. =118.= Eastward from Mauritania the plain becomes narrower, the rivers fewer, and the soil less fertile, so that no great state, even if it had originated there, could have long maintained itself. The north-eastern corner of the continent, however, is the richest and most valuable of all the lands it contains. This is owing to the great river which, rising in the highlands of Abyssin´ia, and fed by the perpetual rains of Equatorial Africa, rolls its vast body of waters from south to north, through a valley three thousand miles in length. Every year in June it begins to rise; from August to December it overflows the country, and deposits a soil so rich that the farmer has only to cast his grain upon the retiring waters, and abundant harvests spring up without further tillage.