In 2002, Mohammad Yusuf, a young charismatic preacher creates Jama’t Ahl as-Sunnah lid-Da'wah wal-Jihad, in Borno State in north-east Nigeria. The group is more commonly known by its moniker Boko Haram, meaning "Western education is sin."
In 2009, after falling out with then Borno State governor Kashim Shettima, he is arrested and killed in police custody along, with 900 of his followers.
After the Nigerian government's crackdown on Boko Haram, Abubakar Shekau, one of Mohammed Yusuf students, takes control of the group that has radicalised into underground militant cells.
Under Shekau’s leadership, Boko Haram conducts its first suicide bombings against churches and mosques in northern Nigeria.
As Goodluck Jonathan ascends to the presidency in 2010, the group continues to target security personnel. In 2012, Jonathan declares a state of emergency in three north-eastern states.
Jonathan grows unpopular in the region due to to the failure of his administration to tackle poverty, low literacy rates and security issues.
In 2013, the crisis escalates as the group becomes a regional threat, carrying out cross-border attacks in the far north of Cameroon and around the Lake Chad basin.
According to Human Rights Watch, by December 2013, 130 villages have been attacked and are controlled by the group.
The crisis reaches its zenith as Boko Haram declares a so-called Islamic State in north-east Nigeria. Shekau and his men control large swathes of land estimated to be the size of Belgium.
In April 2014, Boko Haram kidnaps 276 girls from Chibok in north-east Nigeria. The incident fuels an international outcry against Boko Haram as activists mobilise to campaign for the return of the young victims.
According to the United Nations, Boko Haram-related violence caused more than 7,831 deaths in 2014 alone, internally displaced almost one million people, and created 130,000 Nigerian refugees in Cameroon, Niger and Chad.
On January 3-7, 2015, the group commits its worst massacre to date, burning at least 2,000 people alive in the border town of Baga in north-east Nigeria.
The group swears allegiance to Daesh in March 2015 and changes its name to Islamic State of West Africa Province (ISWAP).
Nigeria's newly elected President Muhammadu Buhari reshuffles the military leadership and sets December 2015 as the deadline to defeat Boko Haram.
A regional intervention led by Chadian forces with the participation of Niger, Nigeria and Cameroon starts gaining momentum against the group.
Boko Haram rapidly loses control of territory and the Nigerian government states that it has severely weakened the group, claiming that its fighters are hiding in the Sambisa forest.
In August 2016, Daesh announces that it has appointed Abu Musab al Barnawi, the son of founder Mohammad Yusuf, as the new leader of Boko Haram.
Shekau challenges the appointment, leading to a split into pro-Barnawi and pro-Shekau supporters.
The group continues to conduct sporadic attacks across the Lake Chad basin area. The United Nations Children's Fund (UNICEF) reports that 27 children were used in suicide attacks by Boko Haram in the first three months of 2017.
According to the UN, the Lake Chad basin crisis is worsening as 10.7 million are in need of humanitarian assistance in Niger, Chad, Cameroon and Nigeria. 2.4 million people are displaced, including 1.4 million children. Meanwhile, 7.1 million are suffering from acute food insecurity.