At the end of the 90s, the Boko Haram sect began as a protest movement in response to corruption among northern governors responsible for implementing Sharia law. Its supporters demanded full application of Koranic law and rejected the “modernity” of southern Nigeria, whose misguided “education” was considered a sin. In 2003, Yusuf and his followers created a rural community called the “celestial city” in the state of Yobé. They were driven out by the local population and expelled from the state. Many relocated to Maïduguri in Borno, where their contact with authorities quickly deteriorated under the strain of sporadic confrontations. In July 2009, security forces killed hundreds of sect members, including Mohammed Yusuf. Boko Haram radically changed. The sect became an ultraviolent organisation; it widened the spectrum of its targets and gradually extended its geographic range to include, by 2014, almost the entire northern half of Nigeria.