There was a civilization collapse before, around 500 C.E. Cities abandoned, books burned, technology forgotten. It took 1000 years to get back to the level of

There was a civilization collapse before, around 500 C.E. Cities abandoned, books burned, technology forgotten. It took 1000 years to get back to the level of that civilization. People living off the land only have so much time in the day. Some of the causes of collapse included military spending, constant wars, erosion of traditional polytheistic values by intolerant religion, government corruption and political instability, lead pollution, soil erosion and deforestation.