Your challenge, should you take it, is to completely wipe out any political entity that is larger than a petty kingdom. Make the entire world, from Japan through China, India and Germany to Iberia, and from Scandinavia, the Middle East to Ethiopia and then to South Africa, and in the Americas also, completely balkanized into small principalities, petty kingdoms, feuding warlords, city-states, independent local communes, and marauding tribal bands. Thousands of polities, the largest ones consisting of only around a million citizens.
There is no POD limit, and you can do whatever you like with it so long as the entire world will be divided into these small entities.