Western Empire

The or, also called the  was an ancient empire that controlled much territory in a completely different continent to the east of the shinobi lands, during the era of the Sage of the Six Paths.

Overview
The Western Empire was a very expansive and renowned world power across the ocean from the current shinobi lands, prior to the advent of ninjutsu and shinobi themselves. The empire's origins and how it came to acquire much territory are largely unknown, though it's rumored its expansion was halted by Kaguya Ōtsutsuki herself, implying it already existed during Kaguya's era and even that the empire might have tried to expand its borders overseas into the eastern lands. During this time, it had the symbol of a yellow sun with a red spiral and circle on the middle over a red background for its standard, which is said to have belonged to the empire's first ruling dynasty. Sometime after humans began to use chakra, shinobi uprisings began to take place all over the empire. It was during this time Saimei Ōtsutsuki's husband and current emperor was murdered at the hands of rebels, prompting his wife to ascend to the throne due to being childless. Using her superior Ōtsutsuki chakra, Saimei and her branded armies eventually crushed all the insurgents, restoring the empire to glory once more. After Saimei's ascension, the empire's standard was changed to a pattern composed of several magatama in a circle around three more circles decreasing in size towards the center, where two tomoe resided; this pattern was seen inside the same sun icon as the previous one in Saimei's armies' battle standards, though it was also seen without the sun icon in some occasions.

After Saimei left for the eastern lands and ended up being sealed by her cousins, the empire began to slowly crumble under its theocratic regency, essentially having long dissolved into several unaffiliated petty kingdoms by Naruto's age, to the point barely anyone besides fanatic historians recall its existence.

Trivia

 * The Western Empire bares some similarities to the real-life Roman Empire. Both are ancient empires considered world powers during their time, and both eventually crumbled into non-existence.