Xenophon's On Horsemanship Neck Guard

[Paullus Scipio]

Xenophon is speculating on ways to make their armour better. There is nothing to suggest that his ideas were implemented.

While Dan's generalisation is a little too sweeping in my view, it would appear to be true that the cavalry of mainland Greece were evolving from lightly protected horsemen into genuine 'heavy cavalry' exemplified later by Thessalian or Macedonian heavy cavalry, armoured and using a hand-to-hand lance in place of javelins, and who did not 'stand off' to fight. Under Alexander, this would come as something of a rude shock to Persian cavalry, who were in the main unarmoured and fought at a distance with 'paltai'/javelins.

Xenophon [Art of Horsemanship XII.8] goes on to describe protection for the horse as well:

"[8]Since the rider is seriously imperilled in the event of his horse being wounded, the horse also should be armed, having head, chest, and thigh pieces: the last also serve to cover the rider's thighs. But above all the horse's belly must be protected; for this, which is the most vital part, is also the weakest. It is possible to make the cloth serve partly as a protection to it.
[9] The quilting of the cloth should be such as to give the rider a safer seat and not to gall the horse's back.

Thus horse and man alike will be armed in most parts."

Xenophon was probably influenced by the panoplies of Persian aristocrats he had seen in Anatolia, and perhaps in Cyrus' army, who are often depicted on friezes and coins (often at the head of lighter cavalry, and riding down Greek-type hoplites! ) - see below. The thigh protection which also protected the sides of the horse were often called 'parapleuridae'/chaps.

Certainly Dan is correct to the extent that we don't see these 'proto-cataphract' cavalry in mainland Greece, so Xenophon's ideas were not generally adopted in their entirety.