The "Bolous" or "Belous" lived in the plains to the north "right up to the foot of the mountains," and these are the people (according to Mr. Longworth Dames) who, hailing originally from the Caspian provinces, are the typical Baluch tribespeople of to-day.

These mountains, which Idrisi calls the "cold mountains," extend to the north-west of Jirift and are "fertile, productive, and wooded." "It is a country where snow falls every year," and of which "the inhabitants are virtuous and innocent." There have been changes since Idrisi's time, both moral and physical, but here is a strong item of evidence in favour of the theory of the gradual desiccation which has enveloped Southern Baluchistan and dried up the water-springs of Makran. What Idrisi called the "Great Desert" is comprehensive. All the great central wastes of Persia, including the Kerman desert as well as the basin of the Helmund south of the hills, the frontier hills of the Sind border up to Multan, were a part of it, and they were inhabited by nomadic tribes of "thieves and brigands."

Modern Seistan is a flat, unwholesome country, distributed geographically on either side of the Helmund between Persia and Afghanistan. It owes its place in history and its reputation for enormous productiveness to the fact that it is the great central basin of Afghanistan, where the Helmund and other Afghan rivers run to a finish in vast swamps, or lagoons. Surrounded by deserts, Seistan is never waterless, and there was, in days which can hardly be called ancient, a really fine system of irrigation, which fertilized a fairly large tract of now unproductive land on the Persian side of the river. The amount of land thus brought under cultivation was considerable, but not considerable enough to justify the historic reputation which Seistan has always enjoyed as the "Granary of Asia." This traditional wealth was no doubt exaggerated from the fact that the fertility of Seistan (like that of the Herat valley, which is after all but an insignificant item in Afghan territory) was in direct contrast to the vast expanse of profitless desert with which it was surrounded—a green oasis in the midst of an Asiatic wilderness.

The Helmund has taken to itself many channels in the course of measurable time. Its ancient beds have been traced and mapped, and with them have been found evidences of closely-packed townships and villages, where the shifting waters and consequent encroachment of sand-waves leave no sign of life at present.

Century after century the same eternal process of obliteration and renovation has proceeded. Millions of tons of silt have been deposited in this great alluvial basin. Levels have changed and the waters have wandered irresponsibly into a network of channels westward. Then the howling, desiccating winds of the north-west have carried back sand-waves and silt, burying villages and filling the atmosphere for hundreds of miles southward with impalpable dust, crossing the Helmund deserts even to the frontier of India. There is no measurable scale for the force of the Seistan winds. They scoop up the sand and sweep clean the surface of the earth, polishing the rounded edges of the ragged walls of the Helmund valley ruins. It is a notable fact that no part of these ruins face the wind. All that is left of palaces and citadels stands "end on" to the north-west. For a few short months in the year the wind is modified, and then there instantly arises the plague of insects which render life a burden to every living thing. And yet Seistan has played a most important part in the history of Asia, and may play an important rôle again.

Arab records are very full of Seistan. The earliest of them that give any serious geographical information are the records of Ibn Haukel, but there are certainly indications in his account which engender a suspicion that he never really visited the country. He mentions the capital Zarinje (of which the ruins cover an enormous area to the east of Nasratabad, the present capital) and writes of it as a very large town with five gates, one of which "leads to Bist." There were extensive fortifications, and a bazaar of which he reckons the annual revenue to be 1000 direms.

There were canals innumerable, and always the wind and the windmills. It is curious that he traces the Helmund as running to Seistan first and then to the Darya-i-Zarah. This is in fact correct, only the Darya-i-Zarah (or Gaod-i-Zireh, as we know it) receives no water from the Helmund until the great Hamún (lagoons) to the north of Nasratabad are filled to overflow. He also mentions two rivers as flowing into the Zarah—one from Farah (an important place in his time), which is impossible, as it would have to cross the Helmund; and one from Ghur. This indicates almost certainly that the name Zarah was not confined, as it is now, to the great salt swamp south of Rudbar on the Helmund, but it included the Hamúns north of Nasratabad, into which the Farah River and the Ghur River do actually empty themselves. At present these two great lake systems are separated by about 120 miles of Helmund River basin, and are only connected occasionally in flood time by means of the overflow (called Shelag) already referred to. The mention of Bist, and of the bridge of boats across the river at that point, is important, for it is clear that about the year A.D. 950 one high-road for trade eastward was across the desert, i.e. via the Khash Rud valley from Zarinje to about the meridian of 63 E.L. and then straight over the desert to Bist (Kala Bist of modern mapping). The further mention of robats (or resting-places) en route, indicates that it was well kept up and a much traversed high-road. Subsequently Girishk appears to have become the popular crossing-place of the river, but it is well to remember that the earlier route still exists, and could readily be made available for a flank march on Kandahar.

From Idrisi's writings we learn that a century later, i.e. about the end of the eleventh century, the Seistan province extended far beyond its present limits. Bamian and Ghur (i.e. the central hills of Afghanistan) were vis-à-vis to that province; Farah was included; and probably the whole line of the frontier hills from the Sulimanis, opposite Multan, to Sibi and Kalat. It was an enormous province, and a new light breaks on its traditional wealth in grain and agricultural produce when we understand its vast extent.

The regions of Ghur and Dawar bordered it to the north, and there is a word or two to be said about both hereafter. Ghur in the eleventh century included the valley of Herat and all the wedge of mountainous country south of it to Dawar, but how far Seistan extended into the heart of the mountain system which culminates to the south-west of Kabul it is difficult to say. It is difficult to understand the statement that Bamian, for instance, bordered Seistan, with Ghur in between, unless, indeed, in these early days of Ghur's history (for Ghur was only conquered by the Arabs in A.D. 1020, and was still far from intertwining its history with that of Ghazni when Idrisi wrote) the greatness of Bamian overshadowed the light of the lesser valleys of Ghur, and Bamian was the ruling province of Central Afghanistan. This, indeed, seems possible. The district of Dawar to the south of Ghur has always been something of a mystery to geographers. Described by Idrisi as "vast, rich, and fertile," and "the line of defence on the side of Ghur, Baghnein, and Khilkh," it would be impossible to place it without a knowledge of the towns mentioned, were it not that we are told that Derthel, one of the chief towns of Dawar, is on the Helmund, and that one crosses the river there "in order to reach Sarwan." This at once indicates the traditional ford at Girishk as the crossing-place, and Zamindawar as the Dawar of Idrisi. Khilkh then becomes intelligible also as a town of the Khilkhi (the people who then occupied Dawar, described as Turkish by Idrisi, and probably identified with the modern Ghilzai), and finds its modern representative in the Kalat-i-Ghilzai which crowns the well-known rock on the road from Kandahar to Kabul. "The country is inhabited by a people called Khilkh," says Idrisi. "The Khilkhs are of a Turkish race, who from a remote period have inhabited this country, and whose habitations are spread to the north of India on the flank of Ghur and in western Seistan." Thus the position of the Ghilzai in the ethnography of Central Afghanistan appears to have been established long before the days of Mongol irruption. Then as now they formed a very important tribal community.

It is, however, sometimes difficult to reconcile Idrisi's account of the routes followed by his countrymen in this part of Asia with existing geographical features. Deserts and mountains must have been much the same as they are now, and the best, if not the only, way to unravel the geographical tangle is to take his itinerary and see where it leads us. Of Baghnein on the southern borders of Seistan, he says it is an "agreeable country, fertile and abundant in fruits." From there (i.e. the country, not the town) to Derthel one reckons one day's journey through the nomad tribes of Bechinks, Derthel being "situated on the banks of the Helmund and one of the chief towns of Dawar."