EMPIRE (imperium), in political geography, a large extent of land, under the jurisdiction or government of an emperor. In ancient history we read of four great monarchies or empires, namely, that of the Babylonians, Chaldeans, and Assyrians; that of the Medes and Persians; that of the Greeks; and that of the Romans. The first subsisted from the time of Nimrod, who founded it in the year of the world 1800, according to the computation of Usher, till that of Sardanapalus their last king in 3257, and consequently lasted above 1450 years. The empire of the Medes commenced under Arbaces, in the year of the world 3257, was united to that of the Babylonians