The plain of the ancient Baktria, of which Balkh represents the capital, lies south of the Oxus River, extending east and west for some 200 miles parallel to the river after its debouchment from the mountains of Badakshan. It is flat, with a scattering of prominences and mounds at intervals denoting the site of some village or fortress of sufficient antiquity to account for its gradual rise on the accumulations of its own debris, probably assisted in the first instance by some topographical feature. Looking south it appears to be flanked by a flat blue wall of hills, presenting no opportunity for escalade or passage through them, a blue level line of counterscarp, which is locally known as the Elburz. This great flanking wall is in reality very nearly what it appears to be--an unassailable rampart; but there are narrow ways intersecting it not easily discernible, and through these ways the rivers of the highlands make a rough passage to the plains. Wherever they tumble through the mountain gateways and make placid tracks in the flats below, they are utilized for irrigation purposes, and so there exists a narrow fringe of cultivation under the hills, which extends here and there along the banks of the rivers out into the open Balkh plain. But these rivers never reach the Oxus. This is not merely because the waters of them are absorbed in irrigation, but because there is a well-ascertained tectonic action at work which is slowly raising the level of the plain. Thus it happens that whilst big affluents from the north bring rushing streams of much silt-stained water to the great river, no such affluents exist on the south. The waters of the Elburz streams are all lost in the Oxus plain ere they reach the river. Nevertheless there are abundant evidences of the former existence of a vast irrigation system drawn from the Oxus. The same lines of level mounds which break the horizon of the plains of Babylon are to be seen here, and they denote the same thing. They are the containing walls of canals which carried the Oxus waters through hundreds of square miles of flat plain, where they never can be carried again because of the alteration in the respective levels of plain and river. Ten centuries before Christ, at least, were the plains of Babylon thus irrigated, and just as the arts of Greece and India rose on the ashes of the arts of Nineveh, so doubtless was the science of irrigation carried into the colonial field of Baktria from Assyria, and thus was the city of "Nimrud" surrounded with a wealth of cultivation which rendered it famous through Asia for more centuries than we can tell. Whether or no the science of irrigation drifted eastwards from the west it seems more than probable that the ruined and decayed water-ways which intersect the Balkh plain were primarily due to the introduction of Syrian labour, and account for the presence in that historic region of a people amongst others who claim descent from captive Israelites.