 Complete the following phrase:  From 2009, Boko Haram, a jihadist terrorist organisation based in northeastern Nigeria, waged an insurgency in an attempt to institute an Islamic caliphate in Nigeria. By 2014, violent attacks perpetrated by the group had killed tens of thousands of people. A government crackdown ensued which saw a state of emergency declared in Borno, Yobe and Adamawa. Under pressure, Boko Haram was forced to retreat to rural, mountainous areas where they began to target civilians. Their numbers were bolstered by Islamist militants fleeing from nearby Mali due to a 