This year sees two notable anniversaries. It is the fifth anniversary of the 9/11 attack, and the newspapers are full of commentators(1) trying to work out the relationship between Wahhabism, Al Qaeda and the House of Saud. Meanwhile, in July of this year, a conference(2) of Arab writers gathered in Yemen’s capital Sana’a to mark a little noticed event – the 600th anniversary of Ibn Khaldun’s (1332-1406) death.