Three years had now passed since the death of Darius; Alexander had done in the interior of Asia a work which no western conqueror has accomplished since on so large a scale. Even to-day the effective occupation by Russia of the lands once included in the Persian Empire falls short of Alexander’s achievement, because Afghanistan, included in his conquests, is still an autonomous state. It will have been already noticed that much attention had to be given while the Macedonian army was in these Far Eastern provinces, to their protection against the nomad tribes on their frontiers. These operations in Bactria and Sogdiana were a necessary part of the conquests of Persia, since these remote provinces acted as a barrier against the savage tribes of the central Asiatic steppes, who might at any time by joint action overrun the civilization of the regions south of them. The special care shown by Alexander in the construction of settlements in this region is an evidence of his desire to make them centers of civilizing influence by which the restless herdsmen might be trained to orderly methods of life. The experiment failed, but it was a brilliant vision--a vision which might have become a reality if the conqueror had lived the normal span of years. The beating down of all opposition in the enormously extensive empire which the defeat of Darius had laid at his feet had now been accomplished. If Alexander had been a statesman and nothing else, he would have stayed his hand, because the consolidation of the territory he had overrun was a work demanding the time and the talents of the greatest genius. But Alexander had not the temper of a Roman proconsul, capable and zealous to solve large political problems. He was young enough to be influenced by the spirit of adventure, and unlike Cæsar and Napoleon, had sometimes no deeply laid scheme in his military exploits. There was no political or military necessity summoning Alexander to the conquest of India, but there was the irresistible charm of novelty exerted by the unknown, the ambition to penetrate into regions untrodden before by any Greek, and with this feeling of the conqueror the modern world is able to sympathize. He was lured also by the legendary stories of the visits to India of the god Dionysus and the hero Herakles. The mystical, superstitious traits in Alexander’s character could easily be stimulated, as we have already seen, to emulation with the divinities of his people, and he was also glad to afford proof that he could effect a conquest attempted without success by Cyrus and Semiramis.