Vulcania

Lore Extract 1: Vulcania was founded around -250, however due to a major war had to hide their entire people inside a mountain range for hundreds of years. This war is known as the Extinction War because it wiped out all other nations. They aren't too aggressive however are incredibly powerful and not a force to be messed with. Vulcania's religion is focused around their god, Vulcan, who allegedly forged the world and now hides in volcanoes creating new lifeforms. They have a holy site on top of Mount Vulcan, the tallest mountain in the Vulcanian mountain range, where they will often toss pieces of weaponry for Vulcan to reforge so they can get them back when they go to heaven. Lore Extract 2: Vulcania is not at all expansionist however is a superpower compared to all the other nations as they have 350+ years of technological advancement due to the era they formed in being founded around -500, which is why they were able to beat the horde so easily. This applies to the other nations from the Previous Era as well.