[El_Phil]

Really I wasn't aware of that, developed civilisation in Nigeria. Blimey. It must have fallen apart fairly comprehensively to 'disapear' for all pracitcal purposes. Given the prevelance of copper around there, the Nigerian copper belt was and is huge, I would suspect copper working/smelting. Technical, versitile and significantly different from where Europe was heading towards Iron/Steel.

As for what would have happened had Europeans left Africa alone, it depends when you cut the links I suppose. The number system we use to this day is Arabic not Roman, I do remember something along the lines of Italian city state merchants bringing it back from North Africa. Don't forget ideas and inventions went both ways across the Med, cultures were 'Mediteranean' not 'South European'.