Slavery should have made Africa strong

There is one thing about Africa and slavery that has perplexed me for a long time.  Seeing that the Europeans were able to build great empires out of the slave trade, how is it that Africa too did not become powerful on account of the trade?

Before I begin, I should state very clearly that the morality of slavery is not an issue that should cause any dispute.  When viewed within the context of its time - a time when there was virtually no understanding of the concepts of racial, ethnic or gender equality or the absence of modern technologies that would render slavery obsolete, slavery was appropriate, moral and necessary.  I personally don't have any issue with it when viewed within its correct context.

So, why did those African nations that exported slaves by the millions did not experience the growth in their power like the European nations?  Some historians would want us to think that the Africans were unaware of how the European nations were using slavery to build powerful nations.  However, this is not the case.

African nations like Benin sent their ambassadors to Europe and several African monarchs actually sent their children to Europe to be educated during the period of the slave trade.  Surely, these elite Africans would have seen how Europe was developing on account of the slaves that Africa was exporting.  Why then did they not try to replicate some of what they learned in Europe in Africa?

Africans were also largely aware of what was going on in the West, in respect of the slave plantations that were providing much of Europe's wealth.  For example, Kongo's ambassador to the Vatican in 1604 went to Brazil to free an African who was wrongfully enslaved.  Surely, he would have seen the plantation system at work.

Why then did the African states that were exporting slaves did not see any need to diversify their economies?  Seeing that slavery was a part of African society as it was in the West, it is strange that they did not see, for instance, any need to replicate the plantation system in Africa.  Africa could have been used to produce, on a large scale, agricultural products that could not be produced in Europe – using the western plantation system that they knew about.

Agriculture is not the only area that Africans could have used the contact with Europe on account of the trade to their advantage.  Many of the African nations that exported slaves were only able to do so because of the weapons that the Europeans gave them.  Why was there no effort in any of these African nations to manufacture these weapons?  Why was there no African arms industry for ships, guns and cannons?

I think it is safe to say that our African ancestors squandered many of the opportunities that the slave trade gave them.  The African kingdoms of Ashanti and Benin, for example should have had well-developed agricultural systems, with large slave plantations modeled after those in the West, exporting goods to Europe and elsewhere.  These slave exporting nations should also have had strong manufacturing economies that should have been supplying the African market and perhaps even markets elsewhere.  

I think that a part of the reason for the failure of Africa's slave exporting nations to develop is cultural.  Sadly, we still see this culture today, with the Chinese.  Like the Europeans before, China is taking Africa's resources and Africa is getting comparatively little in return.  Indeed, it wouldn't surprise me if two centuries from now, our African descendants would start demanding reparations from the Chinese for "exploitation".

By the late 19th century those slave exporting countries in West Africa should have been in a very strong state, strong enough to not only resist European conquest, but also strong enough to build their own empires.  Instead, when Europe put the brakes on the slave trade, the economies of those nations crashed.  In many respects, I still cannot understand why.