If you want to know what they're angry about you could try asking the fucking terrorists, or even just listen to what they say. Other than the gys upset about cartoons in every single case it's because of us interfering in their countries (9/11 guys) Israel killing people in neighbouring countries/Palestinians (9/11 and most terrorist attacks previous to that), us invading Afghanistan/Iraq and killing hundreds of thousands ( 99.something percent of attacks since 2001.) Case in point. The people giving interviews to bystanders after they knifed that British soldier. And so on.