Along with the new arrangement of the administration of the empire Darius had transferred the centre of it into a province, which had thrice rebelled against him, to Susa,[433] the ancient metropolis of Elam, which Assurbanipal had conquered, plundered, and destroyed 130 years previously. Since that time the city had risen from its ruins. We have seen what motives determined Darius to take this step. The position of the city, which was not far removed from his native territory, and at the same time brought the stubborn resistance of the Babylonians under the close pressure of the royal residence, offered the requisite security. Out of Media, from the southern foot of the Mount Elvend (Orontes), the Kerkha, or Choaspes, flows down the heights which bound Iran on the west, towards the south-west; and then breaks through them in order to fall into the Tigris. Further to the east is the Dizful. Rising more to the south than the Kerkha it reaches the plains of Elam in a course parallel to that stream and then falls also into the Tigris. Between these two rivers there rises in the mountain edge the Shapur, a river of a short and narrow course, but with a deep channel. For a time it flows in the same direction with the others, then it turns to the east, and falls into the Dizful, or rather into the Karun, as the Dizful is now called in its lower course, after the affluent which falls into it from the east. At the point where the Kerkha and Dizful approach within two or three leagues of each other,--though lower down they separate more and more widely,--about half a league from the east bank of the Kerkha, and on the eastern side of the Shapur, is the city of Susa. The approach from the west was barred by the Kerkha, and from the east by the Dizful and its affluents. If an enemy came from the west or the east, he had to cross considerable rivers. The great road which ran from the west from Sardis to Susa, came to an end opposite Susa on the west bank of the Kerkha. According to Herodotus the city could only be reached by a ferry across the river. This was no doubt an arrangement for security. An approaching enemy was not to find bridges either on the Kerkha or the Dizful.[434] Thus irrigated by three rivers, the land round the city was extraordinarily fruitful and blooming.