“First, among the Illyrians my head was wounded by a stone and my neck by a cudgel. Then at Granicus my head was cut open by an enemy’s dagger, at Issus my thigh was pierced by the sword. Next, at Gaza my ankle was wounded by an arrow, my shoulder was dislocated, and I whirled heavily round and round. Then at Macaranda the bone of my leg was split open by an arrow. . . . Among the Aspasians my shoulder was wounded by an arrow, and among the Gandridae my leg. Among the Mallians the shaft of an arrow sank deep into my breast and buried its steel; and I was struck in the neck by a cudgel.” in Plutarch. The severity of the wounds Alexander received in personal combat are as likely as anything the result of pure chance; the strength of an enemy state comes primarily from their numbers, but only so many can assail the king at any one time, so you quickly hit a point of diminishing returns in terms of personal danger to the enemy commander. One arrow is very much as good as another.No, he reports that it is because of the difficulty of the enemies (the Nanda) lying ahead:
"It was reported that the country beyond the river Hyphasis was fertile, and that the men were good agriculturists, and gallant in war; and that they conducted their own political affairs in a regular and constitutional manner. For the multitude was ruled by the aristocracy, who governed in no respect contrary to the rules of moderation. It was also stated that the men of that district possessed a much greater number of elephants than the other Indians, and that those men were of very great stature, and excelled in valour. These reports excited in Alexander an ardent desire to advance farther; but the spirit of the Macedonians now began to flag, when they saw the king raising one labour after another, and incurring one danger after another."
And should be pointed out that Arrian's statement comes after the hard fought battles of Hydaspes against Porus - who in actuality took advantage of Alexander - and against the well-fortified city of Sangala.
Why didn't the Persians do the same thing then in the centuries in which they ruled the same area as Alexander?
Point to me any wound facing the Thracians comparable to the arrow wound he got in the siege of Multan. The only time outside of India where Alexander was in danger of dying was from his head wound in Gaza. And he died not long after he returned from his Indian campaign.
Regarding the Persians, I'll point out that they must have used their Alexander grade conquerors -mostly Cyrus, who was killed fighting the Massagetae (does that make them stronger than the Indians, who never managed to actually kill Alexander?)- getting to the Aegean, and that even their best troops were probably not quite up to the standards of the Macedonians; Alexander would be young and in his prime if he were to make such an undertaking, with one of the best armies of the ancient world at his back. The Persians were by no means the wimps the outdated historiography likes to paint them as, but the Macedonians were obviously doing something right to beat them in all the major land battles in Asia.
While you can say a conquest of the Nanda is implausible, I think you have to take that with a hefty pinch of salt, considering the sheer, mind boggling implausibility of Alexander even having gotten to India in the first place. Let's face it, he conquered the greatest empire the world had ever seen in about the time it took for him to walk from one end of it to the other. This is a guy to whom our usual bounds of plausibility are more polite suggestions than anything else. Starting fresh from a base in Iran/India, he probably has as good a chance of beating the Nanda in a couple big battles as he did the Persians, with the subject defections following after to further tip the scales in his favor.