The Immortal City Alliance was comprised of over a thousand cities.
Based on a city's size and highest level of martial force, they were divided into four classes: First, Second, Third, and Fourth.
A First-class Immortal City naturally had a Nascent Soul Cultivator presiding over it and a population of ten million—these were the two strict requirements.
There were only twenty First-class Immortal Cities in total.
A Second-class Immortal City, Ruihan City's current classification, had a Nascent Soul Cultivator, but a population of over one million, yet less than ten million.
There were about fifty Second-class Immortal Cities in the Alliance.
A Third-class Immortal City had a population of over five hundred thousand and was presided over by a Core Formation Master.
A Fourth-class Immortal City was also presided over by a Core Formation Master—a city could not be established without one—but had a population of less than five hundred thousand.
