But if Babylonia lay thus open to Lydia, and through Lydia to the _isles_ and _coasts_ of Greece, it was different with her northern frontier. What strikes us here is the immense series of fortifications, which Nebuchadrezzar, in spite of his alliance with Astyages, cast up between his country and Media. Where the Tigris and Euphrates most nearly approach one another, about seventy miles to the north of Babylon, Nebuchadrezzar connected their waters by four canals, above which he built a strong bulwark, called by the Greeks the Median wall. This may have been over sixty miles long; Xenophon tells us it was twenty feet broad by one hundred high.[55] At Sippara this line of defence was completed by the creation of a great bason of water to flood the rivers and canals on the approach of an enemy, and of a large fortress to protect the bason. Alas for the vanity of human purposes! It is said to have been this very bason which caused the easy fall of Babylon. By turning the Euphrates into it, the enemy entered the capital through the emptied river-bed. The triple alliance--Lydia, Media, Babylonia--stood firm after its founders passed away. In 555, Crœsus and Astyages, who had succeeded their fathers at Sardis and Ecbatana respectively, and Nabunahid, who had usurped the throne at Babylon, were still at peace, and contented with the partition of 585. But outside them and to the east, in a narrow nook of land at the head of the Persian Gulf, the man was already crowned, who was destined to bring Western Asia again under one sceptre. This was Kurush or Cyrus II. of Anzan, but known to history as Cyrus the Great or Cyrus the Persian. Cyrus was a prince of the Akhæmenian house of Persia, and therefore, like the Mede, an Aryan, but independent of his Persian cousins, and ruling in his own right the little kingdom of Anzan or Anshan, which, with its capital of Susan, lay on the rivers Choaspes and Eulæus, between the head of the Persian Gulf and the Zagros Mountains.[56] Cyrus the Great is one of those mortals whom the muse of history, as if despairing to do justice to him by herself, has called in her sisters to aid her in describing to posterity. Early legend and later and more elaborate romance; the schoolmaster, the historian, the tragedian and the prophet, all vie in presenting to us this hero "le plus sympathique de l'antiquité"[57]--this king on whom we see so deeply stamped the double signature of God, character and success. We shall afterwards have a better opportunity to speak of his character. Here we are only concerned to trace his rapid path of conquest.