The Arabs entered India and occupied the Indus valley through Makran, and throughout their writings we find, strangely, little reference to any of the Indian frontier passes which we now know so well. But in the north and north-west of Afghanistan, in the Seistan and the Oxus regions, they were thoroughly at home both as traders and travellers; and with the assistance of their records we can make out a very fair idea of the general network of traffic which covered High Asia. The destroying hordes of the subsequent Mongol invasions, and the everlasting raids of Turkmans and Persians on the border, have clean wiped out the greater number of the towns and cities mentioned by them, and the map is now full of comparatively modern Turkish and Persian names which give no indication whatever of ancient occupation. There are, nevertheless, some points of unmistakable identity, and from these we can work round to conclusions which justify us in piecing together the old route-map of Northern Afghanistan to a certain extent. This is not unimportant even to modern geographers. The roads of the old khafila travellers may again be the roads of modern progress. We know, at any rate, that the Arabs of 1000 years ago were much the same as the Arabs of to-day in their manners and methods. Their routes were camel routes, not horse routes, and their day's journey was as far as a camel could go in a day, which was far in the wider and more waterless spaces of desert or uninhabited country, and very much shorter when convenient halting-places occurred. These Arab itineraries are bare enumeration of place-names and approximate distances. As for any description of the nature of the road or the scenery, or any indication of altitude (which they possibly had no means of judging), there is not a trace of it; and the difficulties of transliteration in place-names are so great as to leave identification generally a matter of mere guesswork. One of the most interesting geographical centres from which to take off is Herat, and it may be instructive to note what is said about Herat itself and its connections with the Oxus and Seistan. Herat, says Idrisi, is "great and flourishing, it is defended inside by a citadel, and is surrounded outside by 'faubourgs.' It has many gates of wood clamped with iron, with the exception of the Babsari gate, which is entirely of iron. The Grand Mosque of the town is in the midst of the bazaars.... Herat is the central point between Khorasan, Seistan, and Fars." Ibn Haukel (tenth century) mentions a gate called the Darwaza Kushk, which is evidence that Kushk was of importance in those days, though no separate mention is made of that place; and he adds that the iron gate was the Balkh gate, and was in the midst of the city. The strategical value of the position was clearly recognized.