His name was Ayman, but the couple who brought the boy home to their Iraqi village after buying him for $500 called him Ahmed.
Islamic State militants had killed or enslaved Ayman's parents in their purge of the Yazidi religious minority to which he belongs, then sold the 4-year-old to Umm and Abu Ahmed, who are Muslims.
For the 18 months he lived with the couple, his relatives assumed he was dead, one of several thousand Yazidis who have been missing since the militants overran their homes in what the United Nations has called genocide.