article_snippet: Islamic State has accepted a pledge of allegiance from Nigerian terrorists Boko Haram's who killed 10,000 people in country last year.
article_snippet: We caliph  has accepted the pledge of loyalty of We brothers of Boko Haram's
article_snippet: so We congratulate Muslims
article_snippet: and We jihadi brothers in north-east Africa.'
article_snippet: It said: 'We announce We allegiance to the Caliph... and will hear and obey in times of difficulty and prosperity, in hardship and ease.'