The map of the Oriental world, as thus reconstructed, lasted about a century, though with varying boundary lines; as, for instance, Elam, or Susiana, sometimes formed a part of Babylonia, and at other times of Media. During this period BABYLON was the metropolis of the East. It was raised to greatness by Nebuchadnezzar, who finished the Tower of Belus, raised the Hanging Gardens, and built great palaces. Two-thirds of the bricks unearthed in the ruins of Babylon bear his name. The city formed a square, on both sides of the Euphrates, covering an area of 130 miles, about that of the city and county of Philadelphia. It was surrounded with double walls, one of which is said to have been 300 feet high, and so wide that six chariots could be driven abreast along its summit. The greatness of the city was short-lived. It was taken by the Medes and Persians, B.C. 536, and soon began to decline, though it remained, in a decaying condition, for nearly 1,000 years afterward. [Illustration: BABYLON.] [Illustration: COMPARATIVE AREAS OF THE GREAT EMPIRES--ASSYRIAN, BABYLONIAN, PERSIAN.] [Illustration: THE PERSIAN EMPIRE.] [Illustration: DIVISION OF ALEXANDER'S EMPIRE.] IV. =The Persian Empire=, B.C. 538-330. As the Babylonian power arose with Nebuchadnezzar, the Persian began with Cyrus the Great. He was the hereditary king of the Persians, and headed a revolt against the Medes, which resulted in reversing the relations of the two races, so that the Persians became dominant. He then led his united people westward, and conquered Croesus, the king of Lydia, thus extending his dominion from the Persian Gulf to the Ægean Sea. The power of Babylon began to fall on the death of Nebuchadnezzar, whose successors were weaklings, and in B.C. 538 Cyrus took the city of Babylon. His dominions were now larger than those of the old Assyrian empire; and under his successors the conquests of Persia were pushed both eastward and westward, until, under Darius the Great, they embraced all the lands from the Indus to the Nile. The map represents the empire of Persia at this period, with the twenty satrapies, or provinces, into which it was divided by Darius. This empire lasted for 200 years, until its conquest by Alexander the Great, B.C. 330, when the sceptre of the East passed into European hands, and Greece gave law to Asia. In the extent of its territory, in the strength of its dominion, and in the consolidation of its conquests, Persia was far greater than either Assyria or Babylon. It will be observed that the scale of all the maps of the Assyrian, Babylonian and Persian Empires, is the same, so that their relative proportions may be seen. The map of the Persian Empire represents the political state of the Oriental world at the conclusion of the Old Testament period. When Ezra and Nehemiah were at Jerusalem, and Haggai and Malachi were the prophets of Judah, all the lands were under the dominion of Persia, and were governed from "Shushan the palace," or Susa.