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The group, which may have existed since the late 1990s, organizes under the Muslim cleric Mohammed Yusuf. It is centered in Maiduguri, the capital of the northeastern state of Borno.
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The first known attack by Boko Haram includes roughly 200 militants, who attack multiple police stations in the state of Yobe, near the Niger border.
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The Boko Haram uprising begins in Bauchi and spreads to the states of Borno, Kano and Yobe. The militant group kills scores of police officers. A joint military task force responds, leaving more than 700 Boko Haram members dead and its operational mosque destroyed.
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In the state of Bauchi, 50 Boko Haram militants attack a prison, killing five people and releasing more than 700 inmates.
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Boko Haram targets churches in various states on three Sundays in a row, leaving more than 50 people dead.
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Boko Haram gunmen dress in military uniforms and stage a fake checkpoint near Benisheik in Borno, burning vehicles and executing travelers, leaving at least 143 people dead.
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Boko Haram militants kidnap approximately 276 teenage girls from a boarding school in Chibok in Borno. Officials there say some of the girls were able to escape. The kidnapping sparks global outrage and a #BringBackOurGirls campaign on social media.
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Boko Haram raids the Nigerian town of Damboa. By the time the raid ends, 66 residents have been killed and more than 15,000 have fled.
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In an audio message purportedly from Shekau, Boko Haram pledges allegiance to ISIS, the Islamic militant group which controls areas of Iraq and Syria.
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ISIS publication al-Naba says that Sheikh Abu Musab al-Barnawi is the new leader of Boko Haram. A Boko Haram insider confirms to CNN that al-Barnawi, the son of the group's founder - who was killed by Nigerian security forces in 2009 - is in fact the new leader.
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Scores of people are killed when a Nigerian fighter jet mistakenly bombs a camp for the internally displaced during an operation in Rann against Boko Haram militants, according to Nigerian officials and the Red Cross.