The story of slavery that we are told never includes the role of Islam. The slaves were captured by jihadists and brought to the coast. We have a detailed record of how this took place. Prosperous regions of Africa were destroyed by the Arab slave traders. Out of the slaves that were captured, only 20% of them ever made it to the pens on the coast to be sold.
There is an oddity in the language used in historical record. The words Muslim, Islam and jihad are never used, but only referred to.
We will never understand the slave trade until we understand the Islamic doctrine of slavery.