In James C Scott’s book Against the Grain he describes how the regular collapse of the early Mesopotamian states led to increase in life expectancy among the scattered populations. Densely packed livestock and humans together with a highly stratified society on a monotonous grain based diet often led to pandemics, famines, war and rebellion.
That'd be an interesting book. I'm having trouble seeing an exact connection between a monotonous diet and pandemics. The Chinese didn't seem to have that struggle