Xenophon's On Horsemanship Neck Guard

[Giannis K. Hoplite]

It is proven for everything else however that he describes however, that they were used at some point by some people. He isn't inventing things, he merely mentions everything that he had seen in his vast campaigns in Persia, Thrace and Greece, that seemed to him worthy.
Even his dubious description of the shoulder guard of the right side has its great archeological analogy in the scale cuirass from Bulgaria.

It is very likely that he is describing something that he saw but was never very popular and not depicted.