CHAPTER II. 
DISCOVERIES DURING THE MIDDLE AGES. 
The Arabians. — Their Entrance into Africa ; their Esta- 
blishment on the Niger. — Kingdoms of Ghana, Wangara, 
fyc. — Limits of their Knowledge. — Leo Africanus.— -Changes 
in Central Africa. — Foundation of Tombuctoo. — Descrip- 
tion of that City. — Ghinea. — Melli. — Gualata. 
1 he rise of the Mahometan power, and the vast 
hordes of Saracen invaders which poured into A- 
frica, caused a complete revolution in the moral 
i and political aspect of that continent. This revolu- 
tion, of which the ultimate effect was to extinguish 
all the intelligence, activity, and civilization, by 
which it had been illustrated, showed at first a com- 
pletely opposite tendency. The Caliphate was 
held, during several ages, by a race of monarchs 
who rank among the most accomplished by whom 
any throne has been swayed ; the arts of peace were 
perfected even in the bosom of war, and the na- 
tions placed under their rule, cherished almost a- 
lone the lights of science, which were fast expiring 
in every other region. The migratory spirit of this 
