Chromaticity

Cerulean - The blue kingdom
Vermilion - The red kingdom
Aurelian - The yellow kingdom
Verdant - The green kingdom
Wisteria - The purple kingdom
The different kingdoms all represent different colors. For hundreds of years the kingdoms lived in peace and they all contributed to each other in trade. The Vermilion got power hungry and started trying to take over the other kingdoms. Its been years since the battle has begun and a prophecy has been told that will leave the the savior and unity of the kingdoms to restore peace once more.