"The Negro nations of Africa differ widely as to their manner of life and their characters, both of mind and body, in different parts of that continent, according as they have existed under different moral and physical conditions. Foreign culture, though not of a high degree, has been introduced among the population of some regions; while from others it has been shut out by almost impenetrable barriers, beyond which the aboriginal people remain secluded amid their mountains and forests, in a state of instinctive existence,--a state from which, history informs us, that human races have hardly emerged, until moved by some impulse from without. Neither Phoenician nor Roman culture seems to have penetrated into Africa beyond the Atlantic region and the desert. The activity and enthusiasm of the propagators of Islam have reached farther. In the fertile low countries beyond the Sahara, watered by rivers which descend northward from the central highlands, Africa has contained for centuries several Negro empires, originally founded by Mohammedans. The Negroes of this part of Africa are people of a very different description from the black pagan nations farther towards the South. They have adopted many of the arts of civilized society, and have subjected themselves to governments and political institutions. They practise agriculture, and have learned the necessary, and even some of the ornamental, arts of life, and dwell in towns of considerable extent; many of which are said to contain ten thousand, and even thirty thousand inhabitants,--a circumstance which implies a considerable advancement in industry and the resources of subsistence. All these improvements were introduced into the interior of Africa three or four centuries ago; and we have historical testimony, that in the region where trade and agriculture now prevail the population consisted, previous to the introduction of Islam, of savages as wild and fierce as the natives farther towards the south, whither the missionaries of that religion have never penetrated. It hence appears that human society has not been in all parts of Africa stationary and unprogressive from age to age. The first impulse to civilization was late in reaching the interior of that continent, owing to local circumstances which are easily understood; but, when it had once taken place, an improvement has resulted which is, perhaps, proportional to the early progress of human culture in other more favored regions of the world."[58]