eli5: Why were some ancient cities like Palmyra and Machu Picchu left to ruin and fall apart over hundreds of years instead of being repopulated?

Question

eli5: Why were some ancient cities like Palmyra and Machu Picchu left to ruin and fall apart over hundreds of years instead of being repopulated?

In: 1677

Answer 1

Same reason we have abandoned (or dying out) cities today. Population gradually died off or moved out due to socio-economical reasons, destruction, changes in trade routes, etc. All a city needs to be abandoned is having a highway divert traffic, a railway become derelict, a mine getting closed, etc.