Consider issues of climate. Successful civilizations throughout history have all been based in temperate climates, which allow for mass production of crops. While this is true of some parts of Africa, the African climate has also prevented civilizations from being successful. The Ancient Egyptians were constantly at the mercy of the flooding of the Nile, and the Malian Empire was faced with an expanding Sahara. The African climate is not matched anywhere in the world, and African civilizations had to overcome hostile environments to succeed. In modern Africa, famine and disease still inhibit the growth of societies.
Talk about colonization, which has been a major feature of African history. With the spread of the Arabs and Islam in the eighth century, Africa has been victim to regular colonization, which has prevented civilizations from being successful in the long term. The rise of Europe, and the resulting colonization of Africa, ended indigenous civilizations one by one, concluding with the Zulus in South Africa in the late 18th century.
Look at societal makeup and divisions. Although the traditional tribal method of analyzing African history has been revised in recent years, Africa contains a fractured and diverse population, divided by language, culture and religion. This prevented a major group from uniting the tribes to form a strong unitary state. This was the basis of large civilizations in Europe, Asia and the Americas.
Review the effects of the slave trade, which led to roughly 12 million men being exported between 1450 and 1800. Although this may not have caused devastation to the African continent in terms of demographics, it did prevent a population growth, which is the sign of a prospering civilization. Instead, African society was kept at 1450 levels of population for 350 years, at a time when European birth rate and life expectancy were increasing.