Ring City Placement (RCP) is a new approach to city placement in your empire. Other placement strategies, like OCP, are based on land use patterns. RCP is based on a different principle: reducing corruption.
Thanks to alexman and this thread
Do you think you understand corruption?, we know that corruption has two sources: corruption due to the distance from the capital or forbidden palace, and corruption due to the number of cities.
There is a natural tension between these two: you can achieve low corruption of the first kind by placing many cities very close to your capital (a la ICS), but this means that if you want to exploit all of your land, you need a lot of cities, and the corruption of the second kind is severe. On the other hand, if you try to work all of your land with relatively few cities, to minimize corruption of the second kind, then the cities are spread out and far away.
