'Empire' in the Bible

in those days when King Ahasuerus sat on his royal throne which was at the citadel in Susa [the capital of the Persian Empire],

And when the king's decree which he shall make shall be published throughout all his empire, (for it is great,) all the wives shall give to their husbands honour, both to great and small.

Letters were sent to all the Jews in the hundred and twenty-seven provinces of the empire of Ahasuerus -- words of true peace --