http://www.mrdowling.com/609ancafr.html
A Great Oral Tradition--Ancient Africa 
The European colonial powers called Africa “the Dark Continent” when they began their explorations. They saw it as a vast and dangerous place filled with
savage people, but Africa has been home to many advanced, exotic civilizations. Many have been buried beneath the sands of time, but we know of others, and archaeologists continue to uncover more clues about ancient African civilizations. 
West Africa has a great oral tradition. A griot <http://artsedge.kennedy-center.org/aoi/events/theater/griot.html> is a learned storyteller, entertainer, and historian. Often a griot will memorize the genealogy, or family history, of everyone in a village going back centuries. American writer Alex Haley met a griot in 1966 that had memorized the entire story of the village of Juffure to a date two centuries in the past when his ancestor was enslaved. 
“The old griot had talked for nearly two hours up to then . . . ‘the oldest of these fours sons, Kunta, went away from his village and he was never seen again’ . . . I sat as if I were carved of stone. My blood seemed to have congealed. This man whose lifetime had been in this back-country African village had no way in the world to know that he had just echoed what I had heard all though my boyhood years on my grandma’s front porch in Henning, Tennessee.” 
--Alex Haley, Roots: The Saga of an American Family (1976)
A great deal of what we know about West Africa comes from the griots, but archaeologists are often surprised by new finds. In the last fifteen years, scholars have concluded that civilization had developed in West Africa as much as one thousand years earlier than expected. We now know that Africa had an Iron Age culture with cities and trade routes about 250 years before the common era.
The Nok 
We know very little about the ancient Nok culture of West Africa. We don't even know what they called themselves; Nok is a modern name. We do know, however, that they uncovered the mysteries of iron <http://www.wsu.edu:8080/~dee/CIVAFRCA/IRONAGE.HTM>.
Iron is a metal found in rocks. The Nok discovered that by heating certain rocks, they were able to “smelt” iron. Iron is a very useful substance. Iron is very malleable (or moldable). It can be reshaped for many differentpurposes, including making weapons and plows. Iron conducts heat very well and can be used for cooking and heating. A civilization that had discovered iron would be more advanced than those that had not. The discovery of the uses of iron was a major technological achievement of the ancient Nok of sub-Saharan Africa.
Most ancient cultures discovered copper and bronze before iron, but the Nok apparently moved from the stone age to the iron age. Did the Nok teach themselves these skills, or did they discover the secrets of iron from other cultures? That question remains a mystery that archaeologists may someday understand.