To put it in the context though, it was written during the probably late part of Three Kingdoms period when China wasn't exactly united and prosperous after decades of civil war.
This was also quite possibly written during the crisis of the third century for Rome, where portions of the empire had broken off and they were fractured, so describing it as having many "minor kings" wouldn't have been too inaccurate for the time.
True, though i wouldn't really say there were "many" minor kings, but the distance and info being likely filtered through sources from Sassanid empire which was on the rise during the Shapur reign, influenced that.