Another driving factor is intra-elite competition: http://peterturchin.com/cliodynamica/intra-elite-competition-a-key-concept-for-understanding-the-dynamics-of

Another driving factor is intra-elite competition: http://peterturchin.com/cliodynamica/intra-elite-competition-a-key-concept-for-understanding-the-dynamics-of-complex-societies/ http://peterturchin.com/cliodynamica/intra-elite-competition...