CHAPTER IL 
DISCOVERIES DURING THE MIDDLE AGES. 
The Arabians. — Their entrance into Africa; their Establish' 
ment on the Niger. — Kingdoms of Ghana, Wangara, Sfc. — 
Limits of their Knowledge. — Leo AJricanus. ^Changes in 
Central Africa. — Foundation of Tombuctoo. — Description of 
that City — Ghinea Melli Gualata, 
The rise of the Mahometan power, and the vast 
hordes of Saracen invaders which poured into 
Africa, caused a complete revolution in the moral 
and political aspect of that continent. This revo- 
lution, of which the ultimate effect was to extin- 
guish all the intelligence, activity, and civiliza- 
tion, by which it had been illustrated, evinced at 
first a completely opposite tendency. The Ca- 
liphate was held, during several ages, by a race 
of monarchs who rank among the most accom- 
plished by whom any throne has been swayed ; 
the arts of peace were brought to perfection even 
in the bosom of war, and the nations placed un- 
der their rule, cherished almost exclusively the 
lights of science, which were fast expiring in every 
other region. The migratory spirit of this cele- 
