The article is meant for invaders/occupiers of cities to have an idea of what they are dealing with. The first classification is hierarchical. Hierarchical cities are cities with a chain-of-command power structure, accepted law, and civic responsibility. These cities are the hardest to conquer because of their organization but easiest to govern once in control.
The second type is multicultural. With this Peters means not multi-ethnic but there are different cultures of power which seek control. Imagine pre-Communist China with the government fighting the triads fighting the communists. These cities are difficult to rule and tend to be self-destructive. Only by rewarding one group and making the others love/fear/respect the ruler can these cities artificial survive.
The final type of city is tribal. Tribal cities are a nightmare and do not last long due to their murderous habits. A thousand miniature power groups jockey for control and the old, brutal ways of the country side seep in.
The fact the article was written in 2000 yet applies much to the Iraq War is darkly humorous. A Dr. Pauletta Otis wrote a rebuttal but Peters replied with "Dr. Otis reports her beautiful view of the world from a university campus, so she has the advantage of me. My own views always seem to be crippled by experience." Ouch! Remind Catholicgauze never to debate against Peters.