148 TO RUDBAR AND JIRUFT [Chap. V
Tump-i-Kharg upwards the mounds display on their surface definite evidence of their having been occupied by settlements of the Muhammadan period, and, in the case of Tump-i-Kharg, by one existing during a considerable length of time with a fairly dense population.
These observations seem to point to a gradual shift in the position of the main settlements of the district from the terminal course of the river to ground higher up where an adequate supply of water could be assured with far greater certainty. Considering how closely all economic life in this region is bound up with irrigation, we may well feel inclined to connect that shift with physical changes which in the course of thousands of years affected the volume of the Halil Rûd and thus also the conditions of irrigation dependent on it. But it is obvious also that no definite conclusion can be drawn from the observations above indicated until the stratification of particular mounds has been probed by systematic excavations. Such work alone, moreover, can be expected to answer the question as to whether prehistoric deposits may not lie deeply hidden below the level of the present alluvial surface of the ground.
SECTION III—THE BASIN OF JIRUFT
The name of Jiruft is borne by a portion of the Halil Rûd valley which, owing to the ample supply of water here carried by the river and the width of the valley bottom capable of irrigation, must have at all periods been a notable district within the province of Kerman. The defile through which the Halil Rûd passes near Qasimabad defines the southern limit of a riverine trough which extends in a northerly direction for about 35 miles to where the river is joined by several streams descending from the Jabal Bariz and the high range above Sardûyeh and Rayin. The Halil river is fed largely by the snows of the high Kôh-i-Lalehzar south of Kerman and of the neighbouring ranges, and affords here ample facilities for irrigation. In addition, water is available from gancits tapping the drainage of the Khorgatu chain to the west of the valley and of the Jabal Bariz on the east. It is hence not surprising to find that Muqaddasi and other early Arab geographers give much praise to the Jiruft district for the abundance and variety of its products and the manifold amenities of its chief town bearing the same name.1
Nowadays, after centuries of political insecurity to which the south-eastern portion of the Kerman province has been exposed from both the Afghan and Balûch sides, the cultivated area has become greatly reduced. Much fertile land at the bottom of the valley has turned marshy through disastrous floods of the river, no longer controlled by embankments. But even so the contrast pre-
1 Cf. for translations of full extracts, Schwarz, Iran im Mittelalter, pp. 240 sqq.