One thing that's puzzling me about the Nigerian OC groups is how they're formed along tribal lines and what the predominant background of these groups are.
When you do some search about Nigerian crime in general you'll find that a lot of communities in Nigeria seem to talk down on the Igbo people, accusing the Igbo of being the community that's predominantly behind the drugs, prostitution, scams, etc...
I wonder if that really is the case since complete information on this is scarce?