Cataphracts development

[Aryaman2]

Xenophon, Anab I.8 says that Cyrus body guard of picked cavalrymen 600 strong had their horses protected by coverings for the forehead and chest, so horse armour was already used by Persians at that time (edit I think Stephanos already cited that passage)
I guess that Scythian armoured cavalrymen would be horse archers though, while the Persians, from Xenophon description, threw javelins and then closed with swords. Probably also Scythian armour would be more leather than metal.