RTF is a global modification that replaces all towns in the game.

It might exist, but it's clearly in decline – things are so bad that Asche only worships Arantir, and the others don't care.

As far as I understand, Erish consists of many free cities, ruled by particularly powerful necromancers. Necromancers usually don't show much activity, but sometimes they engage in small skirmishes for some reason. Once every few hundred years, a special necromancer appears, unites everyone, and goes to war with someone.

Added 1 minute ago

Well, in principle, Arantir was a beacon of light for necromancers.... By the way, how did things go with Mother Namtaru during his reign?

She didn't really rule; she was more of a symbol (like the English queen).