General Haig during the progress of his surveys, we know pretty certainly where the course of the Lower Indus must have been, and where both Scylax and Nearkos emerged into the Arabian Sea. The Indus delta of to-day covers an area of 10,000 square miles with 125 miles of coast-line, and it presents to us a huge alluvial tract which is everywhere furrowed by ancient river channels. Some of these are continuous through the delta, and can be traced far above it; others are traceable for only short distances. Without entering into details of the rate of progression in the formation of Delta (which can be gathered not only from the abandoned sites of towns once known as coast ports, but from actual observation from year to year), it may be safely assumed that the Indus of Alexander and Scylax emptied itself into the Ran of Kach, far to the south of its present debouchment. The volume of its waters was then augmented by at least one important river (the Saraswati), which, flowing from the Himalayas through what is now known as the Rajputana desert, was the source of widespread wealth and fertility to thousands of square miles where now there is nothing to be met with but sandy waste. As far as the Indus the Persian Empire is known to have extended, but no farther; and it was important to the military advisers of Darius that something should be known of the character of this boundary river.

Wherever the ships sent by Darius may have gone it is quite clear that they did not sail up the Indus, or there would have been no objective for an expedition which was organised to determine where the Indus met the sea by the process of sailing down that river. Moreover, the voyage up the Indus would have been tedious and slow, and could only have been undertaken in the cold weather with the assistance of native pilots acquainted with the ever-shifting bed of the river, which, so far as its liability to change of channel is concerned, must have been much the same in the days of Darius as it is at present. The possibility, therefore, is that Scylax made his way to the Upper Indus overland, for we are told that the expedition started from the city of Carpatyra in the Pactyan country. This in itself is exceedingly instructive, indicating that the Pactyans, or Pathans, or Pukhtu speaking peoples have occupied the districts of the Upper Indus for four-and-twenty centuries at least; and coincident with them we learn that the Aprytæ or Afridi shared the honour of being resident landowners. Nor need we suppose that the beginning of this history was the beginning of their existence. The Afridi may have rejoiced in his native hills ten or twenty centuries before he was written about by Herodotus. We need not stay to identify the site of Carpatyra. The Upper Indus valley is full of ancient sites. A century and a half later Taxilla was the recognized capital of the Upper Punjab, and Carpatyra meanwhile may have disappeared. Anyhow we hear of Carpatyra no more, nor has the ingenuity of modern research thrown any certain light on its position. It is, however, probably near Attok that we must look for it. Scylax made his way down the Indus in native craft that from long before his day to the present have retained their primitive form, a form which was not unlike that of the coast crawling "ships" of Darius. He proved the existence of an open water-way from the Upper Punjab to the Persian Gulf, and incidentally his expedition shows us that the chief lines of communication through the width of the Persian Empire were well known, and that the road from Susa to the Upper Indus was open. The outlying satrapies of the Persian Empire could never have been added one by one to that mighty power without definite knowledge of the way to reach them. It was not merely a spasmodic expedition, such as that of Scylax, which pointed the way to the conquests of the Far East; it was the gathered information of years of experience, and it was on the basis of this experience (unwritten and unrecorded so far as we know) that Alexander founded his plans of campaign.

The detailed list of peoples included in the satrapies of the Persian Empire, whilst it is more ethnographical than geographical in its character, is sufficient proof in itself of the existence of constant movement between Persia and the borderland of Afghanistan, which assuredly included commercial traffic. This enumeration has been compared with a catalogue of tribal contingents which swelled the great army of Xerxes, an independent statement, and therefore a valuable test to the general accuracy of Herodotus; and it is still further confirmed by the list of nations subject to the Persian king found in the inscriptions of Darius at Behistan and Persepolis. We are not immediately concerned with the satrapies included in Western Asia and Egypt, but when Herodotus makes a sudden departure from his rule of geographical sequence and introduces a satrapy on the remotest east of the Persian Empire, we immediately recognize that he touches the Indian frontier.

The second satrapy most probably corresponds with that part of Central Afghanistan south of the Kabul River, which lies west of the Suliman Hills and north of the Kwaja Amran or Khojak. Every name mentioned by Herodotus certainly has its counterpart in one or other of the tribes to be found there to this day, excepting the Lydoi (whose history as Ludi is fairly well known) and the Lasonoi, who have emigrated, the former into India and the latter to Baluchistan.

The seventh satrapy, again, comprised the Sattagydai, the Gandarioi, the Dadikai, and the Aparytai ("joined together"), an association of names too remarkable to be mistaken. The Sattag or Khattak, the Gandhari, the Dadi, and the Afridi are all trans-Indus people, and without insisting too strongly on the exact habitat of each, originally there can be little doubt that the seventh satrapy included a great part of the Indus valley.

The eleventh satrapy is also probably a district of the Indian trans-frontier, although Bunbury associates the name Kaspioi with the Caspian Sea. It is far more likely that the Kaspioi of Herodotus are to be recognized as the people of the ancient Kaspira or Kasmira, and the Daritæ as the Daraddesa (Dards) of the contiguous mountains. All Kashmir, even to the borders of Tibet (whence came the story of the gold-digging ants), was well enough known to the Persians and through them to Herodotus.

The twelfth satrapy comprised Balkh and Badakshan—what is now known as Afghan Turkistan. It was here that, generations before Alexander's campaign, those Greek settlements were founded by Darius and Xerxes which have left to this day living traces of their existence in the places originally allotted to them. In Afghan Turkistan also was founded the centre of Greek dominion in this part of Asia after the conquest of Persia, and it is impossible to avoid the conviction that there was a connection between these two events. The Greeks took the country from the Bakhi; but there are no people of this name left in these provinces now. They may (as Bellew suggests) be recognized again in the Bakhtyari of Southern Persia, but it seems unlikely; and it is far more probable that they were obliterated by Alexander as his most active opponents after he passed Aria (Herat) and Drangia (Seistan).

The sixteenth satrapy was north of the Oxus, and included Sogdia and Aria (Herat). South of Aria was the fourteenth satrapy, represented by Seistan and Western Makran, with "the islands of the sea in which the King settles transported convicts"; and east of this again was the seventeenth satrapy covering Southern Baluchistan and Eastern Makran. It is only during the last twenty-five years that an accurate geographical knowledge of these uninviting regions has been attained. The gradual