Slavery has ravaged African societies since at least 2,500 BCE, from Egypt to the Cape; from Mauritania to Somalia. Most writing covers just one fraction of this history: the horrors of the trans-Atlantic slave trade. Yet Indian Ocean slavery was equally sizeable, and far longer-lived. Historians often neglect the continent's internal practices, too--Ethiopian kingdoms enslaving conquered peoples; the Sokoto Caliphate capturing men and women on a scale matching the US plantations.

Overlooked stories of enslavement matter. In 1794, Congress authorised construction of the US Navy's first six ships--to protect civilian vessels from North Africa's Barbary corsairs, who raided as far as Britain and the Caribbean, enslaving hundreds of thousands of Europeans. And, since abolition of the trans-Atlantic trade, international focus on 'modern' slavery has left Africans enslaved as chattel today with few champions. The UN and African Union are too embarrassed to confront leaders still permitting this practice.

Unbroken Chains is the first full account of the bondage systems that have scarred African communities over the millennia. It is an illuminating, powerful read.