Interesting to see that civilisation does not need to be built on rich and poor in rigid hierachies.Teotihuacan in Mexico thrived for 5 centuries without slaves, slums, or even big differences between rich and poor. This is in contrast to Rome, Egypt, Mycenae, Greece, Babylon, etc.
https://www.reuters.com/article/us-mexico-archeology-teotihuacan-feature/stylish-suburbs-how-ancient-mexican-metropolis-dodged-inequality-trap-idUSKBN1YN0J2