Why can China be designed as a neighboring island (like Japan), and the Caliphate and the Crusaders fit so well into an RPG setting, but what about the Goths?
In general, you could also include countries of Warlocks, Sorceresses, and Elementals, as in Heroes 3. You could make the Elves into Ice Elves, as Mugais has such a race in his new ideas. IMO, the more races, the better!

China is unnecessary; I don't like Eastern mythology. The Caliphate – no, because mages live in deserts. And besides, in Heroes 5, each race has its own god. Goths are not very appealing. I think it would be good to create clans for the Vampires.
They will be at war with each other. Warlocks = High Elves, Sorceresses, and others will live in a magical university on an island together with Sea Elves. And Ice Elves could be the Dwarves (in Heroes 3) or Falmer. They could be placed in the mountains.