There are no practical irrigation engineers in the world (excepting perhaps the Chinese) who can rival the Afghans in their knowledge of how to make water flow where water never flowed before. It is of course impossible, on such evidence as we possess as yet, to claim more than the appearance of a probability based on such an undeniable possibility as this. After the death of Darius his kinsman Bessos escaped into his own satrapy (probably to Balkh), and there assumed the upright tiara, the emblem of Persian royalty, taking at the same time the name of Artaxerxes. True to his invariable principle of leaving no unbeaten enemy on the flank of his advance, Alexander proceeded to subjugate Hyrkania, from which country he was separated by the Elburz (Persian) mountains. He crossed those mountains in three divisions by separate passes, and effected his purpose with his usual thoroughness and without much difficulty. Having crushed the Mardians he shaped a straight course eastward to Herat on his way to Baktria, marching by the great highway which connects Tehran with Mashad. The country around Mashad (part of Khorasan) was a satrapy of Persia under Satibarzanes, who submitted without apparent opposition and was confirmed in his government. The capital of this province was Artakoana, described as a city situated in a plain of exceptional fertility where the main roads from north to south and from west to east crossed each other. To no place does such a description apply so closely as Herat, and it has consequently been assumed that Herat indicates more or less closely the site of the ancient city Artakoana, which, indeed, is most probable. But Alexander had not long passed that city in his march towards Baktria when the news of the revolt of Satibarzanes reached him with the story of the loss of the Macedonian escort which had been left with that satrap and had been massacred to a man. He immediately turned on his tracks, captured Artakoana, routed the satrap, and by way of leaving a permanent monument of his victory founded a new city in the neighbourhood which he called Alexandreia. This is probably the actual origin of the modern Herat, and it is a tribute to the sagacity of the Macedonian King that from that time to this it has abundantly proved its importance as a strategical and commercial centre.