cause of the country’s present state of sordid desolation.  That the decay was gradual was not the fault of the rivers, but was due to the sound principles on which the old system of control had been evolved through many centuries of labour.  At the time of the Moslem conquest the system had already begun to fail.  In the fifth century there had been bad floods; but worse came in A.D. 629, when both rivers burst their banks and played havoc with the dikes and embankments.  It is related that the Sassanian king Parwiz, the contemporary of Mohammed, crucified in one day forty canal-workers at a certain breach, and yet was unable to master the flood.(2) All repairs were suspended during the anarchy of the Moslem invasion.  As a consequence the Tigris left its old bed for the Shatt el-Hai at Kut, and pouring its own and its tributaries’ waters into the Euphrates formed the Great Euphrates Swamp, two hundred miles long and fifty broad.  But even then what was left of the old system was sufficient to support the splendour of the Eastern Caliphate.

(1) Cf. Letters of Hammurabi, Vol.  III, pp. xxxvi ff.; it was the duty of every village or town upon the banks of the main canals in Babylonia to keep its own section clear of silt, and of course it was also responsible for its own smaller irrigation-channels.  While the invention of the system of basin-irrigation was practically forced on Egypt, the extraordinary fertility of Babylonia was won in the teeth of nature by the system of perennial irrigation, or irrigation all the year round.  In Babylonia the water was led into small fields of two or three acres, while the Nile valley was irrigated in great basins each containing some thirty to forty thousand acres.  The Babylonian method gives far more profitable results, and Sir William Willcocks points out that Egypt to-day is gradually abandoning its own system and adopting that of its ancient rival; see The Near East, Sept. 29, 1916, p. 521.

     (2) See Le Strange, The Lands of the Eastern Caliphate, p.
     27.

The second great blow to the system followed the Mongol conquest, when the Nahrwan Canal, to the east of the Tigris, had its head swept away by flood and the area it had irrigated became desert.  Then, in about the fifteenth century, the Tigris returned to its old course; the Shatt el-Hai shrank, and much of the Great Swamp dried up into the desert it is to-day.(1) Things became worse during the centuries of Turkish misrule.  But the silting up of the Hillah, or main, branch of the Euphrates about 1865, and the transference of a great part of its stream into the Hindiyah Canal, caused even the Turks to take action.  They constructed the old Hindiyah Barrage in 1890, but it gave way in 1903 and the state of things was even worse than before; for the Hillah branch then dried entirely.(2)