When China started importing cotton from Egypt in 1956, few imagined that just half a century later China’s widening grasp of a huge range of different commodities in Africa, from iron ore in Gabon to cocoa in Ivory Coast and crude oil in Angola, would reshape the continent’s economics.

At the recent first African Commodities Exposition in Beijing, Wen Jiabao, China’s prime minister, predicted that China and Africa would multiply that initial $12m trade in cotton half a century ago to $100bn by 2010.