It's a nuanced article - some interesting quotes from this are:
"In 1492, the Spaniard Christopher Columbus discovered for Europe a 'New World'. The find proved disastrous not only for the 'discovered' people but also for Africans. It marked the beginning of a triangular trade between Africa, Europe and the New World. European slave ships, mainly British and French, took people from Africa to the New World. They were initially taken to the West Indies to supplement local Indians decimated by the Spanish Conquistadors. The slave trade grew from a trickle to a flood, particularly from the seventeenth century onwards.Portugal's monopoly in the obnoxious trade was broken in the sixteenth century when England followed by France and other European nations entered the trade. The English led in the business of transporting young Africans from their homeland to work in mines and till lands in the Americas."
"The vast majority of slaves taken out of Africa were sold by African rulers, traders and a military aristocracy who all grew wealthy from the business. Most slaves were acquired through wars or by kidnapping. The Portuguese Duatre Pacheco Pereire wrote in the early sixteenth century after a visit to Benin that the kingdom "is usually at war with its neighbours and takes many captives, whom we buy at twelve or fifteen brass bracelets each, or for copper bracelets, which they prize more." Olaudah Equiano, an ex-slave, described in his memoirs published in 1789 how African rulers carried out raids to capture slaves. "When a trader wants slaves, he applies to a chief for them, and tempts him with his wares. It is not extraordinary, if on this occasion he yields to the temptation with as little firmness, and accepts the price of his fellow creature's liberty with as little reluctance, as the enlightened merchant. Accordingly, he falls upon his neighbours, and a desperate battle ensues...if he prevails, and takes prisoners, he gratifies his avarice by selling them." "
"If there were no buyers there would be no sellers."
"To highlight the role of the African elites in the slave trade is not to argue the obvious that they were morally depraved like the Europeans who bought slaves from them. It is to show that the corrupt leadership that undermines democracy and economic development in African countries today has a long history."