The third hour in the series marks an era of great commercial and manufacturing growth throughout several regions on the continent. It begins with the revolutionary transformation of North and West Africa. On the shores of the Sahara Desert, farmers, traders, warriors and nomads turned this region into the crossroads of some of history's most advanced, and wealthiest, civilizations. Intricate networks of long distance trade would link up productive commercial centers established by rulers of empires and kingdoms. Strolling the streets of the Medina of Marrakesh in present-day Morocco, a walled city within the city, host Henry Louis Gates, Jr. explains how a collection of mud-brick huts became a sophisticated metropolis of trade in the 11th century through the story of Abdallah Ibn Yasin, a Muslim Berber. Ibn Yasin sought to bring the teachings of his faith to the Sanhaja of the Sahara Desert. When faced with resistance, he withdrew and traveled across the Sahara to found the Almoravid ("the people of the frontier fortress") movement.
