Isis: The Origins Of Violence In this authored historical investigation, historian Tom Holland traces the origins of Isis's extreme violence, which it claims is justified by the tenets and scriptures of Islam. Travelling from Paris to Istanbul and from Sinjar to Cairo, he examines the roots of Isis's interpretation of notions such as jihad and caliphate, and examines the origins of the group's beliefs. Holland also questions whether the group's ideology is in part a reaction to a westernisation of Islam that ultimately dates back to the time of Napoleon.