In Mauritania, northwestern Africa, slavery is a fact of modern life. It's estimated that 10-20 percent of the country's 3.5 million people are still enslaved in a system rooted in ethnic discrimination.
Many long-established Arab rulers were toppled during the Arab Spring in 2011. But not all of them: the Sultan of Oman has been head of the Gulf state for forty years – and is as popular as ever. By Anne Allmeling