Parts of sub-Sahara Africa traded with the Arabs, long before the Europeans arrived. Arab trade relationships were not based on unequal and exploitative terms as were European trade relationships with Africa. There was limited economic integration between the continent and the outside world before the 15th century, but for the most part Africa enjoyed relative economic self-sufficiency and autonomy, both gone once the Europeans began colonizing and enslaving Africans. Europeans were after gold and trade routes that Arabs controlled.
Moreover, hegemony over the Indian Ocean that was the key to commercial success. Africa was an incidental arena, but one that proved very profitable for Europe that enjoyed the military tools to colonize Africa. The process of Africa's integration with Europe started the process of underdevelopment which means that the development of the Iberian peninsula was taking place as a result of the colonial empire that Portugal and Spain established in Africa, Latin America and Asia. The ports of Lisbon and Cadiz were the key to overseas colonies, but those ports were also the link with northwest Europe where much of the Iberian gold and silver eventually ended up. Just for the record, scholarship in this field owes a great deal of gratitude to Fernand Braudel, especially his monumental work La Méditerranée et le Monde Méditerranéen a l'époque de Philippe II (3 vols).
While people commonly mistake the concept of underdevelopment with the concept of 'undeveloped', let us clarify that Africa was "undeveloped" before European colonization, but became underdeveloped afterward and remains so to this day. What does it mean to go from 'undeveloped' to underdeveloped? 1. slavery-based labor system; 2. native land appropriation by colonizers; 3. transition from self-sufficiency to monocultural economic process that the colonizers impose a division of labor intended to serve the metropolis.
Whereas sub-Sahara Africa was organized into tribes and lacked the military means to defeat the invading Europeans, it was very difficult for any country in the world to subject Communist China to 'underdevelopment', because it had nuclear weapons, the world's largest standing army, the world's strongest state structure, and a highly organized managed economic structure and supporting institutions. All of this was lacking in China from the First Opium War until Mao too over in 1949. The idea that China in the recent past proves that dependency theory, despite all its limitations, is outmoded is indeed simplistic and absurd.
It is true that slavery is slavery no matter what the particular circumstances, but is there a difference between slavery under Muslims and Christians, is it all the same, and who has responsibility for Africa's exploitation in the past 500 years - Muslims or Christians? Early Egyptians (estimated as early as 3,500 BC) engaged in slave raids in Africa. Muslims continued in the 7th or more likely 8th century the trans-Saharan slave trade, especially promoted by Ghana, Mali, Songhai, and Kanem-Bornu. Europeans added the following in the African trans-Atlantic slave trade that makes it different than what the Arabs were doing.
First, I wonder if this argument can stand on scholarly grounds, given that the military, economic and political power that Europe exercised over Africa cannot possibly be compared with the minimal role of Arabs who themselves became victims of European colonization.
Second, I wonder if such arguments are not intended to lessen the monumental responsibility that Europe had in the last five centuries and continues to have to this day, and will have throughout this century in exploiting Africa. Third, where is the scholarship that makes such claims?
One last point on statistics. It is impossible to know numbers of the slave trade and not a single source is accurate. There are African-American who claim that the trans-Atlantic slave trade involved as many as 30-36 million people, and that one-third perished on the way or shortly after arriving in the Western Hemisphere. Throwing out statistics on how many slaves the Muslims trade vs. how many Christians traded is futile, and it makes more sense to look at the forest and not the trees. The tragedy is that Europe continues to exploit Africa (see my postings on agriculture and fishing), and it will continue to so in the 21st century.