Why was the Persian state called the country of the countries of Darius 1 was called the King of Kings?

Why was the Persian state called the country of the countries of Darius 1 was called the King of Kings? Did you want to be satraps or ears of a king? What feelings does the history of the Persian kingdom evoke?

This is due to the fact that the Persian Empire included many captured countries, so the ruler of the empire was called “the king of kings”. I would like to be a satrap in the Persian Empire. Naturally, the history of the Persian state evokes a sense of greatness, because it was able to become one of the largest and most powerful countries in the Ancient East.