In April 2014, the Nigerian-grown extremist group Boko Haram abducted nearly 300 young girls from a school in northeastern Nigeria, prompting an international movement to "Bring Back Our Girls." Now, many have been sold into a medieval kind of slavery, forced to become brides of Boko Haram fighters. Meanwhile, Boko Haram has formed an alliance with the Islamic State group in Syria and Iraq and increased the level of violence in Nigeria and its neighboring countries. Follow this developing story of Islamic extremism through the AP's stories and images.