Contributor(s): Professor Ian Morris | 20,000 years ago, ‘international relations’ meant interactions between tiny foraging bands; now it means a global system. Philippe Roman Chair Ian Morris explains how the growth of the international system and the shifts of power within it are linked to geography and energy extraction. In tracing this story, Professor Morris asks: Why were the world’s greatest powers concentrated in western Eurasia until about AD 500? Why did they shift to East Asia until AD 1750? Why did they return to the shores of the North Atlantic? And where will they go next? Ian Morris is Philippe Roman Chair in History and International Affairs at LSE IDEAS for 2015-16. Michael Cox is Director of LSE IDEAS. LSE IDEAS (@LSEIDEAS) is a foreign policy think-tank within LSE's Institute for Global Affairs.