I met four former slaves.
One of the reasons I wanted to see South Sudan was that I wanted to speak with locals liberated from North Sudanese slavery. Christian Solidarity International arranged for me to interview former slaves. They also provided an interpreter.
The subject of slavery fascinated me all my life. I could tell you the usual story of the sophisticated European liberal who obviously opposes all forms of slavery but the truth is most sophisticated European liberals don't. Slavery is alive and well in many places and most Europeans and Americans couldn't care less. Few people are interested enough even to read about slavery, even fewer could be bothered to voice an opinion about actual slavery (rather than the concept of slavery which is universally condemned).
But the truth is, slavery exists; and most slaves are still Africans. And the slavers are Africans too although in the case of Sudan they are Afro-Arabs, descendants of Arab colonisers.
Read more here: http://www.desertpenguin.org/south-sudan/slavery.html