To see how geography and ideology collide, consider the ominous plain that is the Turkish-Syrian border. On one side is a Nato country. On the other, for long stretches, are the jihadis of the Islamic State of Iraq and the Levant.
And yet when it comes to topography, the border is a non-event. The mountains that mark Turkey’s frontier with Iraq are absent here. Slipping across could barely be easier — a huge problem not just for Ankara but also for the western countries that live in fear of Isis.
Tim Marshall’s book is a reminder of the salience of geography in international affairs — of the threats such open plains continue to pose in this age of Predator drones and cyber attacks. Countries’ relations with their neighbours are still dictated by their physical characteristics, he argues. So Russia remains preoccupied by Poland’s 300 mile wide plain, a key battleground for armies pushing east and west; China by Tibet.