Now it is certain that no Arab traveller, crossing the Helmund desert from the west by the direct route recently exploited in British Indian interests below Kala Bist and south of the river, could by any possibility have reached a grape-growing and highly-cultivated country in one day's journey. The inference, then, is tolerably clear. Arab traders and travellers never made use of this southern route. Nor should we ourselves make use of such a route as that _via_ Nushki and the Koh-i-Malik Siah, were we not forced into it by Afghan policy. The natural high-road from the east of Persia and Herat to India is _via_ the plains of Kandahar and the ford of Girishk, and the Arabs, with all Khorasan at their feet, were not likely to travel any other way.
Undoubtedly the system of approach to the Indus valley, open to Arab traffic from Syria and Bagdad, most generally used and most widely recognized was that through the Makran valleys to Karachi and Sind, whilst the inland route, _via_ Persia and Seistan, made the well-known ford of the Helmund at Girishk, or the boat bridge at Kala Bist, its objective, and passed over the river to the plains about Kandahar. But it is a very remarkable, and possibly a significant, fact that the continuation of the route to Sind and the Indus valley from the plains about Kandahar is not mentioned by any Arab writer. Did the Arabs descend through any of the well-known passes of the frontier--the Mulla, Bolan, Saki-Sarwar, or Gomul--into the plains of India? Possibly they did so; but in that case it is difficult to account for so important a geographical feature as the frontier passes of Sind being ignored by the greatest geographer of his day.
Following Idrisi's description of the Helmund province we have a brief itinerary from the Helmund ford (Derthel or Benjawai) to Ghazni, said to be nine days' journey inland. None of the places mentioned are to be identified in modern maps except Cariat, which is more than probably Kariut, a rich and fertile district in the Arghandab valley in the direct line to Kalat-i-Ghilzai. This route passes well to the north-east of Kandahar, which was apparently of little account in Idrisi's days. Although there are extensive ruins at Kushk-i-Nakhud, indicated by a huge artificial mound half-way between Girishk and Kandahar, there is nothing in Idrisi's writings by which they can be identified.