Ducitora

Ducitora, or popularly known among the Five Kingdoms as the Iron Empire is a massive Kingdom across the Ocean from the continent where the Five kingdoms are located. It is ruled by Empress Azura. She oversaw the transformation and technological advancement of the realm. While the Five Kingdoms seem to resemble Medieval Europe, Ducitora, particularly Marossi, the capital seems to look more like a typical advanced Western City. Due to it's technological edge over the Five Kingdoms, it also has the superior military. This military edge enabled them to threaten the very existence of the Five Kingdoms before the events of Book 1. This threat was the main reason why Queen Adriana Rys of Stormholt sought to unite the five kingdoms.

Its status as an Empire (compared Stormholt, Bellmere, Abanthus, Fydoria and Ebrimel which are "Kingdoms") and its massive size suggest it might have been divided into several smaller kingdoms in the past and Ducitora may have conquered all of them.